Revision Deck Flashcards
What is Popper’s theory of falsification?
Theories can never be confirmed by empirical tests, only falsified.
Falsifiability = criterion for distinguishing science from non-science.
What is the hypothetico-deductive spiral?
Observation -> theory -> empirically testable hypotheses -> theory modification.
What defines a true experiment?
Causation can be inferred most easily when the suspected causal factor is manipulated (i.e., a “true experiment”).
and the influences of all other “contaminating” factors or artifacts are excluded.
What is data linkage?
preparing data for statistical or qualitative analysis
e.g.
averaging response latencies over several trials
expressing raw scores as percentages or proportions (NB: Simpson’s Paradox).
standardising scores (e.g., expressing in standard deviation terms, i.e., converting to z scores).
log transformations.
collapsing scores into categories (e.g., median split into high vs. low scorers).
forming composites.
What is the difference between correlation does not equal causation and covariation does not equal causation?
A reliable statistical association is not enough to demonstrate causation.
This holds true:
whatever statistical analysis is used (e.g., correlation coefficient, regression, ANOVA).
even in well-controlled, ‘true’ experiments
What are the four alternative explanations to X causes A?
Coincidence
X ->A.
Confounding Variable.
Underlying Construct.
What are the three attributes of relationships?
Direction (pos/neg)
Strength
Form (linear, curvilinear/exponential, cyclical)
What is the difference between a factorial and non factorial research design
Factorial: All IVs crossed with each other over each level to form cells
Non-Factorial: one or more IVs have levels that are not crossed
How do you test interactions with continuous IVs?
Plotting groups at 1SD above and below mean, predictors
What defines an Ordinal Interaction?
- The lines do not cross, AND
2. The lines do not slope in opposite directions.
What defines a disordinal interaction?
- The lines cross, AND
2. The lines slope in opposite directions.
What is the requirement for an unclassified interaction?
Meeting only one of the criteria for a disordinal interaction
Why does it matter what kind of interaction there is?
A predicted disordinal interaction (without main effects) is a very strong result, because:
It’s more difficult to find an alternative explanation to fit the opposing simple effects.
A predicted ordinal interaction (2 main effects) is weakest.
Measurement artifacts or other alternative explanations may account for the results.
For a predicted “not classified” interaction, it depends.
More vulnerable to alternative explanations than disordinal interactions
What is Generality?
External validity
How do you determine generality limitations?
Revealed by the interaction of a critical IV with a person variable, a setting variable, some aspect of treatment, etc.
Under what circumstances are main effects and interactions not independent?
In categorical-IV studies (e.g., using ANOVA).
If the design is unbalanced
In measured-IV studies (e.g., using moderated regression):
An interaction term (e.g., a x b) may be highly correlated with the individual IVs
What is a hidden interaction?
Sometimes, the effect of a within-Ps IV on a DV (i.e., an IV-DV relation) is collapsed into a difference score and treated as a DV.
The effect of another IV on this DV may be reported as though it is a main effect, when really it is an interaction.
How do you prevent hidden interactions?
Always show all cell means before collapsing
Possible problems with a collapsed IV.
Check the full pattern of results.
What is internal validity?
“The degree to which a study establishes that a factor causes a difference in behaviour. If a study lacks internal validity, the researcher may falsely believe that a factor causes an effect when really it doesn’t.”
What are threats to internal validity?
Alternative explanations of an association (usually confounds)
What is the difference between design-related confounds and procedural confounds?
Design-related- occur from design decisions
Procedural confounds are introduced in the procedure and generally cannot be predicted.
What is a counter confound?
A counter-confound is a variable that covaries with the IV & the DV such that it could produce a pattern of results opposite to that predicted.
a counter-confound makes your experiment less sensitive because it works against a significant result for hypothesis
BUT if you do get significant results in the predicted direction, a counter-confound is not a threat to interpretation.
What is a person-variable confound?
Person variable: A pre-existing characteristic of participants that they bring with them to the study.
Confound:
a person-variable (other than a PAV IV) that varies systematically over levels of an IV.
How do you prevent person variable confounds?
(a) Randomly assign persons to IV levels.
(b) Match participants on potential confound + randomly assign.
(c) Vary potential confound & IV(s) factorially.
(d) Match groups on potential confound without random assignment.
What is differential attrition?
When the rate of participant loss over conditions differs systematically and significantly across groups.
What is a testing confound
When the pre-test causes an effect rather than the manipulation/intervention
How do you prevent testing confounds?
a)Vary the treatment between-participants and randomly assign participants to levels of the treatment IV (treatment vs. no treatment).
With random assignment to groups, a pre-test is not necessary for control can avoid the problem.
(b) Use a Solomon Four-Group Design. Half get pre-test, half don’t
What is a sequencing confound?
occurs when exposure to the IV or DV (or associated procedures) causes changes in responding that provide an alternative explanation for the results.
What types of research have a high risk of sequencing confounds?
Experiments on attention & performance, cognitive processes.
Ps complete multiple questionnaires on attitudes, beliefs, etc.
How to prevent sequencing confounds?
(a) Randomly sequence conditions.
(b) Counterbalance condition orders
(c) Vary IV between-participants.
(d) Used fixed sequence that works against the hypothesis.
(e) Use a yoked control.
What is counterbalancing?
Counterbalancing ensures that:
each level of the IV occurs equally often in each available slot, and
every condition precedes every other condition equally often.
What is a contrast effect and why is it problematic?
A participant’s response to a stimulus item may be influenced by the extent of the contrast between the present item and the previously-presented item.
A large change in the IV value from one item to the next may lead to a disproportionately large shift in responding.
Counterbalancing will not account for contrast effects as contrast is not equal
What is asymmetric carryover and why is it an issue?
if A2 is affected by A1 more than A1 is affected by A2
An issue as counterbalancing will not equally alter carryover effects
What are history confounds and what kinds of studies do they affect??
Time- and place-dependent changes that:
happen to occur during the course of the study,
and provide an alternative explanation for the results.
History confounds can affect:
within-participants IVs (mainly).
between-participants IVs.
What are maturation confounds?
Time-dependent changes that:
occur within participants during the course of the study,
and provide an alternative explanation for the results.
How do you prevent within-participants maturation and history confounds?
Control group that receives placebo or no treatment