PSYB04H3 Lecture Notes - Lecture 8: School Violence, Internal Validity, Real Change
Document Summary
Reminder: three things needed to establish causality: temporal order must be correct: cause has to come before outcome, variables have to covary, no other variable is causing the outcome. Internal validity: degree to which we can conclude that the changes in the independent variable caused the changes in the dependent variable. Any factor is the study that allows an alternative explanation for the results is a threat to internal validity. Note (cid:373)aturatio(cid:374) does(cid:374)"t just (cid:373)ea(cid:374) gro(cid:449)i(cid:374)g up it means change that (cid:449)ould ha(cid:448)e o(cid:272)(cid:272)urred a(cid:374)y(cid:449)ays. History happens outside of the person that affects the dependent variable and the solution is to have a comparison group. History affects within-subjects studies if the event affects everyone and between- subjects if it differentially affects one group. Unusually high or low scores followed by measurements that are closer to group mean. The ssolution is to use comparison group, carefully examine data. Testing, participants change the dependent variable due to testing.
