one-group, pretest/posttest design correct answers an experiment in which a researcher recruits
one group of participants; measures the on a pretest; exposes them to a treatment, intervention, or
change; and them measures them on a posttest
maturation threat correct answers a threat to internal validity that occurs when an observed
change in an experimental group could have emerged more or less spontaneously over time
history threat correct answers a threat to internal validity that occurs when it is unclear whether a
change in the treatment group is caused by the treatment or by a historical factor or event that
affects everyone or almost everyone in the group
regression threat correct answers a threat to internal validity related to regression to the mean, a
phenomenon in which any extreme finding is likely to be closer to its own typical, or mean, level
the next time it is measured (with or without the experimental treatment or intervention)
attrition threat correct answers in a repeated-measures design or quasi-experiment, a threat to
internal validity that occurs when a systematic type of participants drops out of a study before it
ends
testing threat correct answers in a repeated-measures experiment or quasi-experiment, a kind of
order effect in which scores change over time just because participants have taken the test more
than once; includes practice effects and fatigue effects
instrumentation threat correct answers a threat to internal validity that occurs when a measuring
instrument changes over time from having been used before. also called instrument decay
selection-history threat correct answers a threat to internal validity in which a historical of
seasonal event systematically affects only the subjects in the treatment group or only those in the
comparison group, not both
selection-attrition threat correct answers a threat to internal validity in which members are likely
to drop out of either the treatment group or the comparison group, not both
observer bias correct answers a bias that occurs when observers' expectations influence their
interpretation of the participants' behaviors or the outcome of the study
demand characteristic correct answers a threat to internal validity that occurs when some cue
leads participants to guess a study's hypothesis or goals. also called experimental demand
double-blind study correct answers a study in which neither the participants nor the researchers
who evaluate them know who is in the treatment group and who is in the comparison group
masked design correct answers a study design in which the observers are unaware of the
experimental conditions to which participants have been assigned. also called blind design