Question

6. What is the main advantage of using a within subjects ANOVA instead if a Between Subjects ANOVA?

why is this advantageous?

Answer 1

Within-subjects factors involve comparisons of the same subjects under different conditions.
Between-subjects factors involve comparisons using different subjects under different conditions.

The main advantage of within-subjects designs is that individual differences in subjects' overall levels of performance are controlled. This is important because subjects invariably will differ greatly from one another.For example If an experiment is conducted comparing four methods of teaching vocabulary and if a one person is used for each of the four teaching methods then  IQ, ability, age and other important variables remain the same in repeated-measures as it is the same person

Other advantages:

• A within-subjects design can use fewer subjects to detect a desired effect size. Further sample size reductions are possible because each subject is involved with multiple treatments. For example, if an independent groups design requires 20 subjects per experimental group, a repeated measures design may only require 20 total.
• Fewer subjects need to be recruited, trained, and compensated to complete an entire experiment.