Types of Studies
A researcher watches children playing on a playground but never interacts with them. What type of non-experimental method is this?
Naturalistic Observation
A study lasts 10 months, and participants improve simply because they grew older.
Which threat is this?
Maturation
A personality test gives very similar results each time someone takes it. Which property is strong?
test-retest
Participants guess the study’s purpose and act in ways they think the researcher wants.
Which bias is this?
What are demand characteristics?
A researcher compares two different groups (seniors vs. freshmen) on stress levels. Which statistical test fits?
independent t-test (determine if there is a statistically significant difference between the means of two independent groups)
A researcher compares kids who already attend private school vs. public school on anxiety levels, but assigns no groups.
What kind of study is this?
quasi-experimental design
A new anxiety program begins the same week a national tragedy occurs that increases everyone’s stress. Which threat occurred?
History Effects
Two different measures of self-esteem are strongly correlated. What type of validity is shown?
convergent validity
(test or measurement accurately measures what it's supposed to by showing it correlates highly with other tests or measures of the same thing)
A puzzle is so easy that nearly everyone gets a perfect score. Which issue occurred?
ceiling effect
A psychologist compares happiness scores across three diets: vegan, vegetarian, and omnivore.
Which analysis should be used?
One-way ANOVA (1 IV, 3+ levels)
A psychologist studies 8-year-olds and 16-year-olds at the same moment in time. Which developmental design is being used?
cross-sectional design
Only the students with the worst grades drop out of a study on academic improvement. Which threat is this?
What is mortality/attrition?
A depression scale does not correlate with an anger scale, showing they measure different things.
Which validity is supported?
discriminant/divergent validity
An experimenter unknowingly smiles more at participants in the treatment group than the control group. Which bias is shown?
experimenter bias
A researcher examines how lighting (dim vs bright) and noise (quiet vs loud) affect reading accuracy.
How many independent variables are there?
A 2×2 factorial design --> have 2 IVs
A researcher follows the same group of children from age 3 to age 18 to study emotional development.
What design is this?
longitudinal study
Participants score extremely low on Test 1 but closer to average on Test 2, even without treatment.
What threat explains this?
Regression to the Mean
A measure accurately predicts final exam scores based on midterm scores. What type of validity is this?
criterion validity (evaluates how accurately a test measures the outcome it was designed to measure)
Only the most motivated people volunteer for a study about self-control. Which bias is this?
self-selection bias
On a graph, two lines are perfectly parallel for the two IVs.
What conclusion can be made?
there is no interaction
Participants are randomly assigned to sleep 4, 6, or 8 hours before taking a memory test.
What type of study is this?
true experimental study
Two classrooms are compared on attention levels, but one class was already high-achieving and the other was already struggling before the study began. What threat to internal validity does this create?
selection effect
A study eliminates all confounds so the IV truly influences the DV. What type of validity is highest?
internal validity
A study compares test performance at 9 AM vs. 4 PM, but the 9 AM group is always in a hot room and the 4 PM group is in a cold room. What kind of confound is this?
confounding variable (temp of room)
A researcher finds that caffeine helps memory only when the task is easy, but not when the task is difficult.
What kind of effect is this?
simple effect (when the effect of one variable only shows up at one level of another variable)