Research Design Flashcards
Predictive value
the degree to which an independent variable can predict a dependent variable
Cohort effects
the effects that might result when a group is born and raised in a particular time period.
Demand characteristic
when subjects act in ways they think the experimenter wants or expects
Experimenter bias (another name)
Rosenthal effect
Hawthorne effect
when subjects alter their behavior because they’re being observed
Selective attrition
when the subjects that drop out of an experiment are different from those that remain. Remaining sample is no longer random
Social desirability
subjects do and say what they think puts them in a positive light.
Frequency distributions
explain how the data in a study looked. Might show how often different variables appeared.
Nominal variables
male/female; Republican/democrat
Ordinal variables
implies order; not necessarily equally spaced (marathon finishers)
Interval variables
show order and space because equal spaces lie between the variables, but do not include a real zero (temperature)
Ratio variables
order, equal intervals, and a real zero (age)
Frequency polygon
plotted points connected by lines; used to plot continuous variables (categories without clear boundaries)
Histogram
vertical bars; sides touch; discrete variables with clear boundaries and interval variables with some order
Standard deviation
(1) subtract mean from each; (2) square each; (3) add; (4) divide by original number of scores; (5) take square root
If standard deviation is large – scores highly dispersed
If small, scores very close together
Unimodal
only one hump
Z-score
how many standard deviations a score is from the mean; -3 to +3 for normal distributions
T-score
transformation of a z-score in which the mean is 50 and the standard deviation is 10; T = 10(z) + 50