Total, Direct and Indirect Effects

a) SAS/Stata Tasks.

i) After using the data with non-missing values, verify that WKDAYR and the twelve functional limitations variables have only valid values (0 to 366 for WKDAYR and 0 “not at all diffi cult to 3 “very diffi cult” for the twelve functional limitations variables).

ii) Create a new variable, FLsum , that is the sum of the twelve functional limitations variables.

iii) Regress WKDAYR on bmiR (We will refer to this as Regression #1 ).

iv) Regress WKDAYR on bmiR and FLsum (We will refer to this as Regression #2).

v) Regress FLsum on bmiR (We will refer to this as Regression #3 ).

b) Write-Up Tasks.

i) Use Regression 2 and Regression 3 to calculate the total, direct, and indirect effects.

ii) Comment on how the total effect calculated in Question 13.1.bi relates to the coeffi cient in Regression 1.