HowToDesignAResearchStudy Flashcards
What are the steps to designing a research design? (How Venerial Disease Overtook My Sexy 3 Aunts Royally)
- Hypothesis
- Variables
- Design
- Operationalizations
- Manipulation
- Setting and Participants
- 3rd Variables (Mediators and Moderators)
- Analyze Data
- Report Results
Hypotheses should be worded as ________ and should make explicit _____ between groups
statements
comparisons
What are the 8 threats to internal validity
- Maturation
- History
- Instrumentation
- Regression Toward the Mean
- Testing
- Selection
- Mortality
- Interaction of Selection x Maturation
Hypotheses should be worded in the past/present/future tense
present or future tense
Describe the internal validity threat: Selection
- Differences in posttest scores exist because of preexisting group differences
- possible unequal distribution of subject-related variables (e.g., sex, race, age, intelligence)
Hypotheses can/cannot be proven
You cannot prove a hypothesis
Describe the internal validity threat: History
- simultaneously occurring outside events may influence subjects
- Events that take place during the course of research that influence the posttest scores
If you include interactions as part of your hypothesis, you need to be explicit about each experimental condition in the interaction. Give an example.
People who work in homogenous groups will perform better than people who work in heterogenous groups
Describe the internal validity threat: Maturation
- Naturally occurring changes in person over time that influence the posttest scores
- Permanent: biological growth
- Temporary: fatigue
What question does the Moderator answer
Answers the question when or for whom does the IV have an influence on the DV
Describe the internal validity threat: Repeated Testing
- Ss may become sensitized
- pretest measurement of the DV may affect the results obtained from subsequent measurements
What question does the Mediator variable answer
- Answers the question how or why does the IV influences the DV
- often a variable that describes an internal psychological mechanism
- Often introduced when there is already a strong relationship between IV and DV
Describe the internal validity threat: Instrumentation
Changes in the way pretest and posttest scores were measured may cause changes in outcome
What should you include when discussing the design of a study
- Name of the design (be specific)
- why it is the best design
- flaws or limitations and how you will attempt to mitigate them
- determine if btwn or within Ss design (state why)
- discuss feasibility (economically, logistically, ethically)
- discuss limitations of feasibility
- design is usually a 2x2 factorial or 2 btwn-Ss factors
Describe the internal validity threat: Regression to the mean
Ss with extreme scores on the pretest will tend to have scores closer to the mean on the posttest
Why do you want to use a 2x2 factorial design
- Economy: the design provides more information from the same amount of work
- Experimental control
- Increases Generality of the results
- A way to investigate interactions among Ivs
*the factorial design allows us to investigate more realistic situations
Describe the internal validity threat: Mortality
Loss of Ss during the experiment that is different btwn the experimental and control groups (e.g., dropping out)
*Differential mortality cannot be ruled out by random assignment
Why is it important to test the interaction of Ivs
Because the effect of an IV rarely occurs in isolation
In the real world, many variables operate simultaneously
Describe the internal validity threat: Selection x Maturation
Differences between groups that cause changes in the groups at different rates
Independent Variable
A manipulation to which participants are randomly assigned (if possible)
What is external validity
The extent to which results fo a study can be generalized from the sample to the population or other settings, samples, and variables
If you cannot manipulation the IV, what types of studies can you do?
quasi-experimental or correlational
Threats to external validity are anything that makes the experimental situation ____
unique
For all levels of the IV, you need to _____
identify the operationalization (even for “absence”)
*be specific (e.g., give quotes of what experimenters will say, if relevant)
_____ experiments have lower external validity; ____ experiments have higher external validity
true, field
Why is it important to run a pilot-test
- Determine if manipulations (IV) have intended effect (i.e., did you manipulate the IV effectively?)
- to find a balance between impact and control
What is ecological validity
whether the research conditions resemble at all the way humans behave in the real world
why is it important to include a manipulation check
to determine if manipulations (IV) have intended effect
What are the 5 threats to External Validity
- Selection x Treatment
- History x Treatment
- Interferences from Multiple Treatments
- Testing x Treatment
- Reactive Arrangements
You should specify what type of data will be produced by the IV.
True/False
True.
Describe the External Validity threat: Selection x Treatment
results are only generalizable to the specific sample studied, not to the general population (e.g., resarch volunteers tend to be different from non-volunteers)
When operationalizing the IV, what should you do to reduce systematic error
- Carefully operationalize variables so that extraneous variables don’t occur with the IV
- Randomly assign subjects to conditions
Describe the External Validity threat: History x Treatment
Because of events going on in the world, the results of the study can’t be generalized to every day life (e.g., doing a study during wartime)
What is the dependent variable
The variable being measured; the variable used to assess the affected construct
Threats to External Validity: What are the three Interferences from Multiple Treatments (in within-subjects designs)
- Carryover effects
- Order Effects
- Practice Effects
When defining the DV, what should you include
- measurement, scale, type of data produced, meaning of high/low scores, reliability and validity of measurement
- be unobtrusive in measurement
- if judges/raters are used, describe criteria for competence and inter-rater reliability
Threats to External Validity: Interferences from Multiple Treatments: What are Carryover Effects
Effects of one treatment contaminate the next (e.g., drug A is still in Ss system when he takes drug B)
What should you do during the manipulation phase of your study?
- describe the research setting
- consent participants
- describe the cover story
- reduce sources of error
Threats to External Validity: Interferences from Multiple Treatments: What are Order Effects
Treatment A alters participants’ response to Treatment B
Threats to External Validity: Interferences from Multiple Treatments: What are Practice Effects
Treatment A teaches participants how to respond to Treatment B
During the manipulation phase, how do you reduce sources of error when designing conditions?
All conditions should be identical except for the IV
Describe the External Validity threat: Selection x Treatment
- The sample is primed by testing and thus not representative of the population
- i.e., the pretest increases or decreases the participants’ sensitivity or responsiveness to the experimental variable such that the pretested sample is no longer representative of the untested population (to which results are to be generalized)
During the manipulation phase, how do you reduce sources of error in terms of experimenter bias?
- Experimenters should be blind to the hypothesis or subject condition
OR
- reduce contact btwn experimenter and subjects
Threats to External Validity: What are the four Reactive Arrangements
- Hawthorne Effect
- Experimenter Expectancy
- Evaluation Apprehension
- Demand Characteristics
During the manipulation phase, how do you reduce sources of error in terms of practice and order effects?
You should consider practice and order effects.
Threats to External Validity: Reactive Arrangements: What is the Hawthorne Effect
Change is a result of being observed and would not really occur in unobserved populations
During the manipulation phase, how do you reduce sources of error when describing the study to Ss?
- Give clear, specific instructions
- explain the purpose of the study
- emphasize its importance
- ensure confidentiality
Threats to External Validity: Reactive Arrangements: What is Experimenter Expectancy
The experimenter communicates their expectations to the subjects implicitly or explicitly
During the manipulation phase, how do you reduce sources of error in terms of rumors about the study?
Control rumors about the experiment
Threats to External Validity: Reactive Arrangements: What is Evaluation Apprehension
Subjects try to avoid negative evaluations
What two things should you do at the end of the manipulation phase
- Manipulation check
- Debrief participants
Threats to External Validity: Reactive Arrangements: What are Demand Characteristics
- Cues provided by the experimental setting that help the subject to develop naïve hypotheses about the experiment’s purpose and to behave accordingly
- When participants behave as they think the experimenter would want them to
Describe what is done during a manipulation check? Give an example of how you can do a manipulation check.
You make sure the IV was perceived by participants in the intended way (e.g., give a questionnaire at the end of the treatment asking Ss about their experience of the study)
What is reliability
How precise is our measure? (the extent to which it is free from random error)
What does it mean to “debrief” participants
You ask them how their participation in the study went; ask them if they have any questions
What are some ways you can increase reliability
- Use heterogenous group of Ss
- Make test items more similar
- Standardize administrations (and avoid context effects and priming - start with neutral, non-threatening items)
- Increase the length of your measure
- Make items and instructions clear (don’t use reverse-worded items, give cover story in everyday language)
After you determine your population of interest, you can get a representative sample through _________
random sampling
Name four ways of assessing reliability
- Test-retest
- Parallel Forms
- Split-Halves
- Internal Consistency Method
When describing your setting and participants, how do you determine how many subjects you need per cell
You do a power calculation. (Jess says you need at least 40-50 Ss per cell)
Describe Test-Retest reliability
- You give the same test twice
- the correlation between the two scores is the reliability (the reliability coefficient)
When deciding who you will and will not include in your study, you should describe __ and __ criteria.
inclusion and exclusion criteria
What are the assumptions and limitations of Test-retest reliability
- assume true score didn’t change
- there are memory effects
- reactivity (from practice effects)
- you assume the tests were parallel
What are some sample demographics you should describe
gender, race, age, other relevant characteristics
Describe Parallel Forms reliability
- You use two different forms
- the correlation between the scores on the two forms is reliability
If you are using a between-subjects design, you can ____ Ss to groups
randomize
What are the Advantages of Parallel Forms reliability
You don’t have to worry about memory effects
If there are important variables that can be identified and measured and equivalence among groups is a problem (even given randomization) what are other ways of equalizing groups using subject variables
matching or blocking
What are the limitations of Parallel forms reliability
- assume true score didn’t change
- assume your error variances are equal
- reactivity (from practice effects)
- it can be difficult to come up with a second test
Define and give examples of moderators
- Moderators can be measured or manipulated
- Usually a demographic-like variable
- answers when or for whom
- (e.g., gender, boring/intersting task, simple/complex task)
Describe Split-Halves reliability
- Administer a single test
- Use 1/2 of the test for one score and 1/2 for the other score
- using the correlation, you will get the “split half” reliability
How do you test for a moderation effect
By creating an interaction term and seeing if it is significant
What are the advantages of uisng Split-Half reliability
You don’t have to worry about:
- stability of the true score (since you only give test once, your score can’t change btwn tests)
- memory effects
- reactivity (practice effects)
it’s cheaper and easier