211 Ch. 10

211 Ch. 10

one-group pretest/posttest
one group of participants, measures on pretest, treatment, posttest, not good!!
maturation
threat to internal validity, when an observed change in an experimental group could have emerged naturally over time
history threats
threat to internal validity, occur when a “historical” or external event occurs to everyone in the treatment group, must occur between manipulation and measuring of DV
regression threat
threat to internal validity, regression toward the mean, any extreme finding is likely to be closer to its own typical mean/level next time it is measured
attrition
threat to internal validity, when people drop out of a study before it ends
testing threat
threat to internal validity, kind of order effect, scores have changed over time because participants have taken the test more than once
instrumentation
threat to internal validity, when a measurement tool changes over time from having been used before
observer bias
threat to internal validity, when researcher’s expectations influence their interpretation of results
demand characteristic
threat to internal validity, when participants guess what the study is supposed to be about and change behavior in expected direction
double blind study
neither participants nor researchers know who is getting which treatment
placebo effect
when people improve, but only because they believe they are receiving a valid treatment
null effect
finding than an IV did not make a difference in DV, that there is no significant covariance
ceiling effects
all scores are at the high end
floor effects
all scores are at the low end
noise
too much unsystematic variability, error variance
measurement error
factors that can inflate or deflate person’s true score on a dependent measure