which is the best method to use to select a covariate in regression? what is the best way to select a variable? when to include time a model in r how to use the r variable selection algorithm? how to select a variable with dx which is an example of variable selection in r which r program should be used to do a linear regression model of time and/or time? how to use lme in r how to select a time model what is the best way to do dynamic covariate in r? how do i find out what the r variable selection is how to select variable from time in r r how to select variables how to select static variables in r can you use forward selection as a covariate can you select variable for a time covariate when using forward selection in r, how to find significant effects how to choose between different variables how to add time and covariates to an r model how to select static variables