why do we use fixed effects and controls simultaneously why do we use fixed effects and controls at the same time why do we use fixed effects and controls at the same time? why do we use fixed effects and controls at the same time why do we use variables and fixed effects in regression why do we use fixed effects and controls at the same time why does it make sense to use fixed effects and controls what is an example of a fixed effect and a control why do we use fixed effects and control variables at the same time why do we add fixed effects and controls why does the model of regression need a fixed effect why do we use fixed effects and controls at the same time? why do we use fixed effects and controls at the same time what's the difference between a fixed effects and a control variable in a regression? why do fixed effects and controls at the same time can fixed effects be used with a control why does ols use fixed effects why are fixed effects and controls used at the same time why is it useful to use fixed effects for regression why do we use variable control and fixed effect