In Simple Repeated Measures designs, SSWS (Sum of Squares for Within Subjects) represents the variation within individual subjects across different conditions. The correct expression for SSWS is:

SSBT – SSResidual

Where:

• SSBT stands for the Sum of Squares Between Treatments (also called Between Groups).
• SSResidual represents the sum of squares for residual or error variation within subjects.

This formula subtracts the residual error from the between-treatments sum of squares to obtain the within-subjects variation, which is the part of the total variation attributed to the differences within subjects themselves.

So, the correct answer is:

SSBT – SSResidual

Would you like further clarification or additional questions? Here are a few related ones:

1. How is SSBT calculated in repeated measures designs?
2. What is the role of SSResidual in determining the significance of effects in repeated measures?
3. How does the structure of repeated measures designs differ from between-subjects designs?
4. What is SSTotal and how does it relate to the components in an ANOVA?
5. How does the assumption of sphericity affect the interpretation of results in repeated measures designs?

Tip: In repeated measures, the main advantage is the reduction in error variance, as each subject acts as their own control, making it easier to detect treatment effects.