what is the focus variable of the multicollinearity? what is the focus variable on firm size why is firm size a focus variable when do you use firm size as a focus variable what is the difference between a focus variable and firm size what is firm size in regression how to deal with multicollinearity why is firm size a control variable if firm size is left out as a focus variable in regression what is firm size used for in pt what is firm size? what is firm size in panel regression what is firm size as control can firm size be a focus variable why is firm size a control variable when firm size is left out in a multicollinear regression what happens if firm size is not considered a focus variable, focus variable becomes highly significant why is firm size in a panel regression is firm size the focus variable on the panel? why is firm size a control variable or focus variable