does a change in the r value affect the significance of a variable in a linear regression why would the f value change if you change the reference group? what is the df value for hdl in regression why would the significance of f-value change if you change the reference group in a linear regression what is the f value of the hdl why would the f-value change if you change the reference group? how would the f value change when you change the reference group in a regression how do you find the significance of fvalue? why does the significance of the f value change when you change the reference group? why will the significance of the f value change in the linear regression if you change the reference group when does f value change in linear regression what is the f value of mdf why does the significance of f value change what is the model for hdl what is the relationship between the f and the reference group in the reg procedure why does f value change in a linear regression which variable can be changed to the reference group during regression what variable has a significance of f in regression what is the significance of f value in a reg? what is the f value for the reg procedure model?