module 12 Flashcards
between subjects design
an experiment in which different subjects are assigned to each group
posttest only control group design
an experimental design in which the dependent variable is measured after the manipulation of the iv
start with a control and experimental group made up of equivalent participants, administer treatment, take a posttest measure
pretest/posttest control group design
dependent variable is measured both before and after manipulation of the iv
solomon four group design
group 1: pretest, treatment, posttest
group2: pretest, posttest
group 3: treatment, posttest
group 4: posttest
confound
if a researcher fails to control for something then the study is open to confounds (uncontrolled variables)
if a study is confounded then it is impossible to say whether changes in the dv are caused by iv or uncontrolled variable
nonequivalent control group
random sampling addresses issues
history
changes in the dv may be due to historical events that occur outside the study
maturation effect
subjects naturally occurring changes could be responsible for observed results
solution: an equivalent control group
testing effect
changes in dv may be due to subjects being tested repeatedly and getting better/worse
solution: equivalent control group
regression to the mean
subjects who are selected because they are extreme on some variable may regress toward mean
solution: equivalent control w/ extremes
instrumentation effect
changes may be due to changes in measuring device
solution: equivalent control group
mortality
differential attrition may lead to inequality in groups
solution: monitor for differential loss
diffusion of treatment
changes maybe to information they received from other participants
solution: testing subjects as close together as possible
experimented and subject effect
experimenters or subjects consciously or unconsciously affect results
solution: double blind or single blind
floor and ceiling effects
measuring instrument used it not sensitive enough to detect differences
solution: ensure that instrument is reliable