Step-wise multiple regression - Relationship between cognitive test performance and walking time.

Step-wise multiple linear regression with the cognitive tests scores as explained variables and walking time, age, gender, education level, height and weight as explanatory variables: a) First step, age and education level are forced into the model, b) Second step, walking time enters the model as first explanatory variable, c) Then, the other confounders (gender, height, weight) were added one by one, R-squared for the final model is given. d) Delta multiple R-squared between second step and first step, all p<0.0001.