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The degree to which a quasi experiment supports a causal statement depends on: random assignment |
B and D |
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Which of the following is NOT one of the reasons why someone would conduct a quasi experiment To take advantage of an opportunity |
To prevent selection effects |
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Which of the following is a difference between true experiments and quasi-experiments? A. Quasi-experiments do not use random assignment. |
A |
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Which of the following is an independent-groups quasi-experimental design? A. Interrupted time-series design |
C |
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In conducting quasi-experimental designs, researchers tend to give up some _____ in exchange for _____. A. Internal validity; external validity |
A |
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In which of the following ways are correlational designs similar to quasi-experimental designs? |
B |
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Which of the following is NOT a small-N design? A. Interrupted time-series design |
A |
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A small-N design that involves providing treatment and then removing treatment is known as a/an: A. Interrupted time-series design |
Reversal |
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In small-N designs, each participant is treated: A. With multiple interventions |
D |
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If a researcher is concerned about external validity, which of the following would you recommend with regard to conducting small-N designs? A. Do not conduct small-N designs if you’re concerned about external validity. |
B |
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Quasi experiment: Independent groups |
-nonequivalent control group design (Posttest-only) -nonequivalent control group design (pretest/posttest) |
|
Quasi Experiments: Repeated measures |
-interrupted time series design -nonequivalent groups interrupted time series design |
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With a quasi experiment you look at both the |
design and the results to evaluate the validity of a causal statement |
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Internal validity in quasi experiments |
-design confounds -order effects -selection effects -maturation -history -attrition -regression to the mean -instrumentation -testing -observer bias -experimental demand -placebos |
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Validity in quasi experiments |
construct and statistical |
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Three small N designs |
1. Stable baseline design 2. Reversal design 3. Multiple baseline design |
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Stable baseline design |
Can we conclude that the expanded rehearsal technique works? |
|
Reversal design |
Can we conclude that the therapy caused her symptoms to improve? |
|
Multiple baseline |
Can we conclude that the overcorrection technique helps this little girl manage her behavior? |
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Validity in Small N designs |
construct and statistical |
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A replication study will NOT help to support external validity when it is a: conceptual replication |
direct replication |
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When using inferential statistics, researchers calculate a/an _____ to determine the statistical significance. A. Effect size |
D |
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Which of the following is NOT a major type of replication? A. Statistical replication |
A |
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How would a researcher quantitatively summarize a scientific literature? Review article |
meta analysis |
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Responsible journalists do which of the following as it pertains to discussing replicability? A. They report only on studies that have been directly replicated. |
C |
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The notation "p < .05" indicates which of the following? A. Mark conducted the study correctly. |
D |
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Which claim is most likely to be tested in generalization mode? Frequency claim |
Frequency claim |
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When an experiment is run in an artificial lab setting it A.must be replicated in a field setting to be generalizable. |
B |
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_____ psychology is a subdiscipline of psychology that works primarily in the generalization mode. A. Clinical |
Cultural |
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Which of the following is another term for ecological validity? A. Mundane realism |
A |
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According to the textbook, what’s the problem with WEIRD samples? A. They’re not very representative of the world’s population. |
A |
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Which of the following is a reason that psychologists especially value meta-analyses? A. Meta-analyses can examine conceptual and direct replications. |
D |
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Inferential statistics |
statistically significant results are considered "replicable" |
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Replication studies |
1. Direct replication 2. Conceptual replication 3. Replication-plus-extension |
|
Direct replication |
same variables; same operationalizations |
|
Conceptual replication |
same variables; different operationalizations |
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Replication-plus-extension |
same variables, plus some new variables |
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External validity |
comes from how, not how many; we can generalize to other people as well as to other settings |
|
Generalization mode |
-frequency claims Goal: to make a claim about a population -Real world matters ***External validity is essential! Examples: -opinion polls -epidemiological estimates |
|
Theory testing mode |
-association and causal claims Goal: to test a theory rigorously, isolate variables -Prioritize internal validity -Artificial situations may be required -Real world comes later -External validity is not the priority Examples: -Harlows studies -Parent as grammar coach |
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The Belmont Report includes all of the following EXCEPT The principle of respect for persons |
Principle of integrity |
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Which of the following ethical violations proposed by the Belmont Report was NOT committed in the Tuskegee Study? A. Participants were harmed. |
C |
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The need to balance the potential costs and benefits to participants taking part in a research study is to address which principle of the Belmont Report? A. The Principle of Respect for Persons |
C |
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Deception in psychology studies should never be done |
must be followed with a debriefing |
|
The American Psychological Association’s ethical guidelines have _____ principles and _____ standards. A. 3, 10 |
D |
|
Federally-funded animal experimentation Sadly, does not have to worry about ethical violations |
must comply with IACUC guidelines |
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All of the following are true of IRBs in the US EXCEPT: A. They can be found in settings other than colleges and universities. |
C |
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In which of the following situations would written informed consent NOT necessarily be required? A. An observational study that measures walking speed of people entering & exiting buildings. |
D |
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Which of the following is a primary goal of debriefing? A. To prevent researchers from being sued. |
D |
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In addition to being an ethical violation, why are data falsification & fabrication problematic? A. They are impossible to discover. |
B |
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The Belmont Report |
1) Respect for persons – informed consent -protection of vulnerable populations 2) Beneficence – cost benefit analysis for participants -cost benefit for society 3) Justice – how are the participants selected? Do they represent people who will benefit from the study |
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Cumulative Part |
Cumulative Part |
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Explain what it means to reason empirically |
Involves using evidence from the senses (sight, hearing, touch) or from instruments that assist the senses (such as thermometers, timers, photographs, weight scales, and questionnaires) as the basis for conclusions. – Aim to be systematic, rigorous and to make their work independently verifiable by others |
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Appreciate how an understanding of psychological research methods is crucial not only for producers of information but also for consumers of information |
-Think about how often you encounter news stories or look up information -Could be crucial to your future career, you need to be able to interpret published research with a critical eye -Read research to see whats been effective -Predict the future |
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Describe five processes that shape psychological science |
? |
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Explain why psychologists value research based calculations over beliefs based on experience, intuition, or authority |
-Power of systematic comparison -In a controlled study scientists can set up the conditions such that they include at least one comparison group, thereby avoiding confounds -Comparison groups |
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Locate research based information, and read it with a purpose |
? |
|
Differentiate the three types of claims: frequency, association, and casual |
Frequency claims- describe a particular rate or degree of a single variable Ex: 44% of Americans struggle to stay happy Association claims- argues that one level of a variable is likely to be associated with a particular level of another variable. Must involve at least two variables, and the variables are measured, not manipulated. Positive, negative, zero. Ex: shy people are better at reading facial expressions or people who multitask the most are the worst as it or screen time not linked to physical activity in kids Casual claims- goes even further, arguing that one of the variables is responsible for changing the other Ex: music lessons enhance IQ, whiff of rosemary gibes your brain a boost, family meals curb teen eating disorders |
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Ask appropriate questions to help you interrogate each of the four big validates: construct validity, statistical validity, external, and internal |
Construct validity- How well has the researcher measured the variable in question? Statistical- What is the margin of error of the estimates? Is there a difference between groups and how large? Statistically significant? Internal- Was the study an experiment? Temporal precedence? Alternative explanations? External- Is it generalizable? How representative is it? |
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Explain which validates are most relevant for each of the three types of claims |
Frequency claim- external validity Association claim- statistical?? Causal claim- internal validity |
|
Interrogate the construct validity of a study variables |
? |
|
Describe the kinds of evidence that support the construct validity of a measured variable |
? |
|
Explain how carefully prepared questions improve the construct validity of a poll or survey |
Leading question- A type of question in a survey or poll that is problematic because its wording encourages only one response, thereby weakening its construct validity. Double-barreled question- A type of question in a survey or poll that is problematic because it asks two questions in one, thereby weakening its construct validity. Negatively worded question- A question in a survey or poll that contains negatively phrased statements, making its wording complicated or confusing and potentially weakening its construct validity. |
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Describe how researchers can make observations with good construct validity |
? |
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Explain why external validity often matters for a frequency claim |
Because you usually cannot directly check accuracy when interrogating a frequency claim, the best you can do it interrogate the sampling technique used, asking how the researchers obtained the sample. As long as they used random sampling you can be more confident in the external validity of the result |
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Describe which sampling techniques allow generalizing from a sample to a population of interest, and which does not |
**Biased sample can not be generalizable **Representative sample can be generalizable Cluster sampling- A probability sampling technique in which clusters of participants within the population of interest are selected at random, followed by data collection from all individuals in each cluster. Convenience sampling- Choosing a sample based on those who are easiest to access and readily available; a biased sampling technique. Multistage sampling- A probability sampling technique involving at least two stages: a random sample of clusters followed by a random sample of people within the selected clusters. Oversampling- A form of probability sampling; a variation of stratified random sampling in which the researcher intentionally overrepresents one or more groups. |
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Dirty Dozen (threat to internal validity) |
maturation threat a change in behavior that emerges more or less spontaneously over time -people adapt to strange environments, children get better at walking etc. preventing maturation: adding a comparison group history threats result from a historical or external event that affects most members of the treatment group at the same time as the treatment, making it unclear whether the changing in the experimental group is caused by the treatment received or by the historical factor -to be a history threat the external factor must affect everyone or almost everyone in the group not just a few people -ex: why did the campers behavior improve? it could have been the low-sugar diets but maybe they all started difficult swimming lessons in the middle of the week and the exercise tired them out Prevent this: by adding a comparison group regression threat refers to a statistical concept called regression to the means: when a performance is extreme at time 1, the next time that performance is measured (time 2) it is likely to be less extreme- that is closer to a typical or average performance -regression works at both extremes -unusually good performance or outcome is likely to regress downward the next time and an unusually bad performance or outcome is likely to regress upward the next time. -regression pulls an extreme group closer to the mean but regression alone will not cause a group to cross back over the mean to the other extreme preventing this: comparison groups help ALSO along with careful inspection of the pattern of results attrition threat in studies that have a pretest and a posttest, attrition is a reduction in participant numbers that occurs when people drop out before the end -can happen when a pretest and posttest are administered on different days and some people cant make the second day -becomes a problem for internal validity when attrition is systematic that is when only a certain kind of participant drops out – easy to identify and correct -when people drop out of a study most researchers will remove those participants scores from the pretest average -another approach is to check the pretest scores of the drop outs. if they have extreme scores on the pretest, their attrition is more of a threat to internal validity than if their scores are closer to the group average testing threats a specific kind of order effect, refers to the change in participants as a result of taking a test more than once -include practice effects and fatigue effects preventing this: – might abandon the pretest altogether and use a posttest only design – if they do use a pretest they might opt to use alternative forms of the test for the two measurements -comparison group can help too instrumentation threat also called instrument decay, occurs when a measuring instrument changes over time -in observational research the people who are coding behaviors are the measurement tool and over a period of time they might change their standards of judging behavior by becoming more strict or more lenient -another example is when a researcher uses different forms for the pretest and posttest but the two forms are not sufficiently equal preventing this: use a posttest only design -if a pretest/ posttest design is required for other reasons, researchers should take steps to ensure that the pretest and posttest measures are equal -for behavioral coders, researchers might retrain their coders throughout the experiment, establishing their reliability and validity -to control problem for different forms, could also counterbalance the versions of the test |
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Possible obscuring factors of a null effect |
chart |
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Within groups design |
Within groups design there is only one group of participants and each person is presented with all levels of the independent variable Advantage ensures the participants in the two groups will be equivalent Within groups covariance, temporal precedence, internal validity Disadvantages of within group designs 1) repeated measured designs have the potential for order effects which can threaten internal validity 2) Might not be possible or practical 3)When people see all levels of independent variable and then change the way they would normally act |
|
Independent groups design |
Independent groups design in which different groups of participants are placed into different levels of the independent variable |
|
debriefed |
they were carefully informed about the studys hypotheses |
|
the belmont report: principles and applications |
commission was called partly in response to the violations in the Tuskegee syphilis study -contributor produced a short document called the belmont report, which outlines three main principles for guiding ethical decision making: 1. respect for persons 2. beneficence 3. justice |
|
respect for persons |
includes 2 provisions 1. individuals participating in research should be treated as autonomous agents: they should be free to make up their own minds about whether they wish ti participate in a research study -every participant is entitled to the precaution of informed consent: each person learns about the research project, knows the risks and benefits, and decides whether to participate -researchers are not allowed to mislead people about the studys risks and benefits nor are they allowed to coerce or unduly influence a person into participating in research -coercion occurs when researchers explicitly or implicitly suggest that those who do not participate will suffer a negative consequence -undue influence occurs when researchers offer an incentive too attractive to refuse 2. state that some people have less autonomy so they are entitled to special protection when it comes to informed consent -children, people with intellectual or developmental disabilities, and prisoners should be protected |
|
beneficence |
researchers must take precautions to protect research participants from harm and to ensure their well-being. they must also consider who might benefit or be harmed -will a community gain something of value form the knowlege this research is producing? will there be costs to a community if this research is not conducted? -to apply this, reseachers must attempt to predict the risks and benefits of their research- both to participants and to the larger community |
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justice |
calls for a fair balance between the kinds of people who participate in research and the kinds of people who benefit from it -when it is applied, it means that researchers might first ensure that the participants involved in a study are representative of the kinds of people who would also benefit from its results |
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APA ethical principles |
this set of guidelines governs the 3 most common roles of psychologists: research scientists, educators, and practitioners 1. beneficence and nonmaleficence 2. fidelity and responsibility 3. integrity 4. justice 5. respect for persons rights and dignity |
|
10 specific ethical demands |
APA lists 10 ethical standards. these standards are similar to enforceable rules or laws. if you violate any of them you can lose your professional license or may be disciplined in some other way by the association. ethical standard 8 is the most relevant one in a research methods book, it is written specifically for psychologists in their role as researchers |
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institutional review boards ( standard 8.01) IRB |
a committee responsible for interpreting ethical principles and ensuring that research using human particpants is conducted ethically -most colleges and universities as well as hospitals and other institutions that conduct research have an IRB -in US IRBs are mandated by federal laws. if an institution conducts research using federal money than a designated IRB is required. -IRB panel includes 5 people: 1. scientist 2. one must have academic interests outside the sciences 3. one or more should be a community member who has no ties to the institution 4. one must be recruited as a designated prisoner advocate ( when the IRB discusses a proposal to use prison participants) 5. some of whom must come from specified backgrounds before conducting a study, researchers must fill out a detailed application describing their study, its risks and benefits, its procedures for informed consents and its provisions for protecting peoples privacy- even describing for how and how long the data will be stored IRB oversight provides a neutral, multi-perspective judgement on any study ethicality |
|
informed consent (standard 8.02) |
informed consent is the obligation to explain the study to potential participants in everyday language and give them a chance to decide if they want to participate -everyone who wishes to participate signs two copies of the document ( one for the researcher to store and one for participant) -in certain circumstances, APA standards indicate that informed consent procedures are not necessary -may not need to have them sign it if the study is not likely to cause harm and if it takes place in an education al setting -written informed consent might not be needed when particpants answer a completely anonymous questionnaire -written consent forms may not be needed when the study involves naturalistic observations of particpants in low-risk public settings such as a classroom or museum or mall -researchers are ethically obligated to inform people of their rights -according to standard 8, obtaining informed consent also involves informing people whether the data they provide in a research study will be treated as private and confidential -nonconfidential data may but people at risk -if data are to be treated as confidential, researchers agree to remove names and other identifiers. such things as handwriting, birthdays, or photos might reveal personal data, and researchers must be careful to protect that info if they have promised so -confidentiality procedures are not optional |
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deception (standard 8.07) |
even in the most straight forward study people may not be told about all the comparison conditions -deception: researchers withheld some details of the study from the participants- deception through omission, in some cases, they actively lied to them-deception through commission -deception is necessary in many cases to get meaningful information and data – APA principles and federal guidelines require researchers to avoid using deceptive research designs except as a last resort, and to debrief particpants after the study |
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debriefing ( standard 8.08) |
when researchers use deception, they must spend time after the study debriefing each participant in a structured convo -in a debriefing session the researchers describe the nature of the deception and explain why it was necessary -non deceptive studies normally include a debriefing session too -they may also offer to share results with the people as well |
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research misconduct |
data fabrication (standard 8.10) and data falsification ^ the two forms of research misconduct data fabrication: occurs when, instead of recording what really happened in a study, researchers invent data that fit their hypotheses data falsification: occurs when researchers influence the studys results, perhaps by selectively deleting observations from a data set or by influencing their research subjects to act in hypothesized way when they fabricate data they mislead others about the actual state of support for a theory. this might inspire other researcher to spend time following a promising (but false) lead. if journalists unknowingly write about fabricated data, it might cause people to wast time on unsupported techniques or therapies. unethical scientists may manipulate their data to coincide with their intuition rather than with formal observations as a true empiricist would -suspect misconduct? report it to the scientists institution. -if the research project is federally funded suspected misconduct can be reported to the office of research integrity a branch of the department of health and human services, then has the obligation to investigate |
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plagiarism |
another form of misconduct is plagiarism usually defined as representing the ideas or words of others as ones own "the appropriation of another persons ideas, processes, results, or words without giving appropriate credit" -it is a form of stealing |
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animal research ( standard 8.09) |
legal protection for laboratory animals psychologists who use animals in research must care for them humanely, must use few animals as possible, and must be sure their research is valuable enough to justify the use of animals -must follow federal and local laws for animal care and protection -the AWA mandates that each institution at which animal research takes place must have local board called the institutional animal care and use committee (IACUC) similar to IRB, they must approve any animal research before it can begin – IACUC must comply with federal guidelines -must contain at least 3 members: 1. veternaitan 2. practicing scientist who is familiar with the goals and procedures of animal research 3. member of the community at large who is unconnected with the institution -the IACUC monitors the care and treatment of animals throughout the research process. it inspects the lab every 6 months |
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animal care and guidelines and the 3 r’s |
use the resources of the guide for the care and use of laboratory animals ( focuses on 3 r’s) 1. replacement: means researchers should find alternatives to animals in research when necessary ( computer simulations) 2. refinement: means researchers must modify experimental procedures and other aspects of animal care to minimize or eliminate animal distress 3. reduction: means researchers should adopt experimental designs and procedures that require the fewest animal subjects as possible -in addition the manual provides guidelines fro housing facilites, diet, and other specifics of animal care research majority of students and psychologist support the use of animals in research -survey suggests that animal researchers are in favor of protecting their animals from pain |
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attitude of animal right groups |
1. they may believe that animals are just as likely as humans to experience suffering -in this view, a certain type of research within animals could be allowed but only if it might also be permitted with human particpants 2. some groups also believe animals have inherent rights, equal to those of humans |
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ethically balancing animal welfare, animal rights, and animal research |
animal researchers defend their use of animal subjects with 3 primary arguments 1. and central argument: is that animal research has resulted in numerous benefits to humans and animals alike 2. supporters of animal research argue that researchers are sensitive to animal welfare 3. researchers have successfully reduced the number of animals they need to use, because they have developed new procedures that do not require animal testing |
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replicable |
responsible researchers always consider whether the results of a study could be a fluke or whether they will get the same result again if the do the study again- want to see if the study is replicable -replicability gives the study credibility -when a researcher performs the study again -3 major types of replication studies: 1. direct replication 2. conceptual replication 3. replication plus extension |
|
direct replication |
researchers repeat an original study as closely as they can to see whether the original effect shows up in the newly collected data -can never replicate the first study in every detail |
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conceptual replication |
researchers study the same research question but use different procedures -at the abstract level, the variables in the study are the same, but the procedures for operationalizing the variables are different |
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replication plus extension |
researchers replicate their original study but add variables to test additional questions -extending an original finding to a new population -another way to introduce a replication study is to introduce a new situational variable |
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replication, importance, and the weight of the evidence |
a single study is important only if it can be replicated -psychological science progresses only as researchers conduct systematic direct, conceptual and replication plus studies |
|
scientific literature |
consists of a series of related studies, conducted by various researchers that have tested similar variables -literatures are composed of several studies on a particular topic, often conducted by many different researchers -the most important conclusions in science are those based on a body of evidence that is a large scientific literature -sometimes researchers collect all the studies on a topic and consider them together- generating what is known as a review article or literature review |
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meta analysis |
a way of mathematically averaging the results of all the studies that have tested the same variables, to see what conclusion that whole body of evidence supports -process of collecting all possible studies on a particular research question and combining them mathematically to study the overall trend in the data researchers can also use a quantitative technique of meta analysis to create a mathematical summary of a scientific literature |
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strengths and limitations of meta analysis |
using meta analysis researchers can also sort a group of studies into categories ( moderators) computing separate effect size averages for each category because meta analyses usually contain data that have been published in empirical journals you can be more certain that the data have been peer reviewed publication bias in psy: significant relationships are more likely to be published than null effects. this phenomenon leads to the FILE DRAWER PROBLEM, the idea that a meta analysis might be overestimating the true size effect because null effects or even possible opposite effects, have not been included in the collection process -to combat this problem: request both published and unpublished data for their product literature reviews and meta are considered valuable by many people because they combine the findings of a variety of studies- direct and conceptual replications into a single average |
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replicability in the popular press |
responsible journalists not only report on the latest studies, they also give readers a sense of what the entire literature says on a particular topic |
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to be important, must a study have external validity? |
reproducing results allows researchers to be far more confident in the accuracy of their results and more convinced of the importance of those results -replicability also helps you interrogate external validity-the degree to which a studies results are generalizable, to both other participants and other settings -although direct replication studies do not support external validity, conceptual replication and replication plus extension studies can external validity: "how" matters more than "how many" |
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generalizing to other settings |
conceptual replications illustrate generalizability to different settings very well |
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ecological validity |
a studies similarity to real world contexts (mundane realism) many psychologists consider ecological validity to be one aspect of external validity |
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theory testing mode |
they are usually testing association or causal claims to investigate support for a theory -external validity matter much less than internal validity |
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generalization mode |
when they want to generalize the findings from the sample in their study to a larger population -concerned about external validity -applied research tends to be done in generalization mode, and basic research tends to be done in theory testing mode frequency claims are always done in generalization mode -representative samples are essential for supporting frequency claims association and causal claims sometimes are done in generalization mode. most of the time they are in theory testing mode cultural psychology: a special case of generalization mode -is a subdiscipline of psychology focusing on how cultural contexts shape the way a person thinks, feels, and behaves. -primarily use generalization mode -cultural psychology challenge other researchers to combine generalization mode with theory testing mode- to test a theory in multiple cultures before assuming it applies to all people |
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theory testing using WIERD participants |
consider that most research in psychological science has been conducted on north american college students participants from these countries are from a unique subset of the worlds population, which researchers refer to as WEIRD: western, educated, industrialized, rich, and democratic -are not very representative of all the worlds people cultural psychologists raise the alarm, reminding researchers that their theories, when tested only on WEIRD people, may not apply to everyone |
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external validity and the real world |
when a study takes place in the real world, sometimes referred to as field study, it has a built in advantage for external validity, because it clearly applies to real world settings -ecological validity is a type of external validity that refers to how similar a studies manipulations and measures are to the kinds of situations participants might encounter in their everyday lives -the emotions and behaviors generated by a laboratory manipulation can also be quite real, visible, and meaningful, -many lab experiments are high in whats known as experimental realism: they create settings in which people experience authentic emotions, motivations, and behaviors |
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generalization mode and the real world |
because external validity is of primary importance when researchers are in generalization mode they might strive for a representative sample of a population -might also try to enhance the ecological validity of their study in order to ensure its generalizability to non laboratory settings -one recent review showed, in fact, that field studies often replicate lab research, especially when the laboratory effect sizes are large |
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theory testing mode and the real world |
when a researcher is working in theory testing mode, external validity and real world applicability are lower priorities -in short, theory testing mode often demands that experimenters create artificial situations that allow them to minimize distractions, eliminate alternative explanations, and isolate individual features of some situation -theory testing mode prioritizes internal validity at the expense of all the other considerations, including ecological validity -nonetheless, such studies make valuable contributions to the field of psychology |
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quasi experiment |
differs from a true experiment in that the researchers do not have full experimental control -might not be able to randomly assign participants to one level or the other -instead participants are assigned to the independent variable conditions by teachers, political regulations, acts of nature- or even by their own choice can be repeated measure design, in which participants experience all levels of an independent variable -the researcher takes advantage of the already scheduled event, a new policy or regulation, or a chance occurrence to manipulate the independent variable construct these experiments to make casual statements |
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nonequivalent control group design |
there are different participants at each level of the independent variable -a quasi experimental study that has at least one treatment group and one comparison group, but participants have not been randomly assigned to the two groups |
|
nonequivalent control group pretest/posttest design |
are not randomly assigned to groups, and were tested before and after some intervention |
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interrupted time series design |
a quasi experimental study that measures participants repeatedly on a dependent variable before, during, and after the "interruption" caused by some event |
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nonequivalent control group interrupted time series design |
it combines two of the previous designs ( nonequivalent control group design and the interrupted time series design) in this example, the independent variable was studied both as a repeated measures variable ( interrupted time series) and as an independent groups variable (nonequivalent control group) in both cases the researcher did not have experimental control over the manipulation of the independent variable or the assignment of participants to conditions |
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internal validity in quasi experiments |
the main concern is internal validity- the researches ability to draw causal conclusions from the results. the degree to which a quasi experiment supports a causual statement depends on TWO things: 1. its design 2. its result to interrogate internal validity, you ask about alternative explanations for an observed pattern of results quasi experiments can take a variety of designs, and the support that a quasi experiment provides for a causal claim depends partly on its design and partly on results. researchers do not have full control of the independent variable in a quasi experiment BUT they choose better designs, and they can use the pattern of results to rule out internal validity threats |
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selection effects |
are relevant only for independent groups designs NOT for repeated measures -applies when the groups at the various levels of an independent variable contain different types of participants -matched groups help counterbalance this effect -wait list design also helps, in which all participants plan to receive treatment, but are assigned to do so at different times |
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design confounds |
in certain quasi experiments they can be a problem -some outside variable accidentally and systematically varies with the levels of the targeted independent variable |
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maturation |
occurs when, in an experimental or quasi experimental design with a pretest and posttest, a treatment group shows an improvement over time, but it is not clear whether the improvement was caused by the treatment or whether the group would have improved spontaneously even without a treatment |
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history |
occurs when external, historical event happens for everyone in a study at the same time as the treatment variable. with a history threat, it is unclear whether the outcome is caused by the treatment or by the common external event or factor -can be extremely relevant when a quasi experiment relies on external factors to manipulate its key variable selection history threat: history threat applies to one group and not the other. the historical event systematically affects participants only in the treatment group or only in the comparison group- NOT BOTH when quasi experiments include a comparison group, history threats to internal validity can usually be ruled out |
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regression to mean |
occurs when an extreme finding is caused by a condition of random factors that are unlikely to happen in the same combo again, so the extreme finding gets less extreme over time remember that regression effects are a threat to internal validity primarily when a group is selected because of its extremely high or low scores. those scores may be extreme because of a combo of random factors that will not occur the same way twice |
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attrition |
in designs with pretest postesets attrition occurs when people drop out of a study over time. becomes an internal validity threat when people drop out of a study for some systematic reason |
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testing and instrumentation threats |
whenever researchers measure participants more than once they need to be concerned about testing threats t internal validity. it is an order effect in which participants tend to change as a result of having been tested before. repeated testing might cause people to improve, regardless of the treatment received. might also cause performance to decline because of fatigue or boredom instrumentation can be internal validity threat when participants are tested or observed twice. a measuring instrument could change over repeated uses, and this change would threaten internal validity you can use a studys results and design to interrogate testing and instrumentation threats to internal validity a comparison group almost always helps rule out a testing threat to internal validity |
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observer bias, demand characteristics and placebo effects |
related to human subjectivity. observer bias- threat to construct validity and internal. threat to internal validity when the experimenters expectations influence their interpretation of the results demand- when participants guess what the study is about and change their behavior in expected direction placebo effects- when participants improve, but only because they believe they are receiving an effective treatment. ^^ these 3 are easy to interrogate observer bias- simply ask who measured the behaviors. was the design blind or double blind? experimental demand- think about whether they were able to detect the study goals and responded accordingly placebo- ask whether the design of a study included a comparison group that received an inert or placebo treatment |
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what does an experimenter gain by using an quasi experiment |
real world opportunities: enable researchers to take advantage of real world opportunities to study interesting and important events external validity: real world settings enhance external validity: the likelihood that the patterns observed in the quasi experiment will generalize to other settings and to other individuals ethics: ethical concerns are another reason they may choose this experiment design construct validity and statistical validity: construct- interrogate how successful the study manipulated or measured its variables. usually show great construct validity for independent variable statistical- could ask how large the group differences were (effect size) and whether the results were statistically significant |
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quasi vs. correlational studies |
quasi experiments: researchers tend to do a little more meddling than they do in most correlational designs in correlational studies they simply select a sample, measure two variables, an test the relationship between them. in quasi experiments they might attempt to achieve internal validity by matching participants, implementing a wait list policy, or seeking out comparison groups provided by nature or by public policy therefore, whereas a correlational researchers primarily measure variables in a sample and analyze their relationships, quasi experimental researchers more actively select groups for an independent variable so they can achieve greater degree of internal validity |
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small n design |
when researchers use a small n design, instead of gathering little info from a larger sample, they obtain a lot of information from just a few cases. they may even restrict their study to only one animal or one person using a SINGLE N DESIGN for the purpose of external validity, how a sample is selected is more important than the samples size: meaning that statistical validity is not necessarily undermined by a small sample take advantage of special medical cases disadvantages: few participants may not represent the human population very well |
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large n v small n ( differences) |
large: 1. participants are grouped: the data from an indivisual participant are not of interest in themselves, data from all participants in each group are combined and studied together 2. data are represented as group averages small: 1. each participant is treated as a separate experiment: small n designs are almost always repeated-measure designs, in which researchers observe how the person or animal responds to several systematically designed conditions 2. individuals data are represented |
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stable base line design |
a study in which a researcher observes behavior for an extended baseline period before beginning a treatment or other intervention -if behavior during the baseline is stable the researcher is more certain of the treatments effectiveness |
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multiple baseline design |
researchers stagger their introduction of an intervention across a variety of contexts, times, or situations -in any format, the multiple baselines provide comparison conditions to which a treatment or intervention can be compared |
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reversal design |
researcher observes a problem behavior both with and without a treatment, but takes the treatment away for awhile to see whether the problem behavior returns by discontinuing a treatment that seems to be working the researcher can test for internal validity and make a causal statement: if the treatment was really working, the behavior should worsen again when the treatment is discontinued appropriate for situations in which treatment would not cause lasting changes |
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evaluating the 4 validities in small n designs |
researchers can take steps to maximize the external validity of heir findings first, they can triangulate by combining the results of a single n studies with other studies on animals or on larger groups second, they can specify the population to which they want to generalize and they can rarely intend o generalize to everyone therefore, they sometimes limit a studys population of interest to a particular subset of possible participants. third, sometimes they are not concerned about generalizing at all -when interrogating a small n you should evaluate construct validity -regarding statistical validity, in a single n design, researchers do not typically use traditional statistics -you might think about effect size more simply in small n cases, by asking: by what margin did the clients behavior improve |
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