a variable that is not controlled in a research investigation
Contrast Effect
When the response to the second condition in the experiment is altered because the two conditions are contrasted to one another.
Counterbalancing
a method for controlling order effects in a repeated measures design by either including all orders of treatment presentation or randomly determining the order for each subject
Fatigue Effect
a deterioration in performance as the reasearch participant becomes bored tired or disoriented
Independent Group Design
an experiment in which different subjects are assigned to each group. AKA- between-subject design
Internal Validity
the certainty with which results of an experiment can be atributed to the manipulation of the IV rather than to some other variable.
Latin Square
technique to control for order effects with out having all possible orders.
Matched Pair Design
method of assigning subjects to groups in which pairs of subjects are first matched on some charachteristics and then individually assigned to groups.
Mortality
loss of subjects who decide to leave an experiment
Order effect
in a repeated measure design the effect that the order of introducing treatement has on the DV
Posttest only design
the expreimental design in which the DV (post test) is measured only once after the manipulation of the IV
Practice Effect
improvement in performance as a result of repeated performance on a task
Pretest Posttest design random assignment
true experimental design where teh DV is measured both before and after manipulation of the IV
Repeated measures design
an experiment in which the same subjects are assigned to each group AKA with in subjects design
Selection differences
differences in type of subjects who make up each group in an experimental desgn. This happens when participants elect which group theyh are to be assigned to.