PSY 230 Lecture Notes - Lecture 2: Confounding, Factorial Experiment, Random Assignment
Document Summary
Chapter 8: experimental design: dependent groups and mixed groups designs. Two kinds of dependent groups designs discussed in class. Matched-groups design matched sets of participants are assigned in such a way that one member of each matched set is assigned to each treatment condition or group. Within-participants design the same participants are used in all treatment conditions. Error variance in dependent groups designs the between-participant variability is reduced which in turn reduces the error variance. Power because dependent groups designs reduce error variance, they are generally more powerful than between-participants designs. May not know what important variable to match participants on (in matched groups). If we lose one member of a matched set then we must eliminate the other members of the matched set from our analysis. Some research problems can"t be tested using a dependent groups design. Participants because the same participants serve in all conditions, you need fewer participants to complete the design.
