psych 2301-experimental design lecture

basic experiment

-obtain two equivalent groups

-introduce independent variable 

-measure effect of independent variable on the dependent variable 

assigning particpamts

1. independent group designs

2. repeated measures designs

3. matched pairs design

independent group design

-different partipants are assigned to each level of the independent variable

-assignemnt to conditions is random

pretest posttest designs

-sample size is small

-need specific particpants for experiement

-likelihood of dropout is high

disadvantage:

-time consuming

-sensitve to partipants

soloman four group design 

-assess the impact of pretest as a second independent variable 

-half particpants recieve pretest and posttest 

half particpants only recieve posttest