what is a fixed affect model what does plm mean when estimating a fixed model what variable does it use which is the model of a fixed effect what is the dummy value within the plm package what is plm? what is the dummy in the fixed effects what is within and within model in plm is within model a fixed effect? what is the name of a fixed effect model? what is the model in plm package what is within and within model? what is within model what is the package of dummy variables called what's the difference between an within and a fixed effect model? can i use within models in plm what is within in plm what does plm do with variable what is the package wihin in? which method is best to use to estimate the volatility of the variable within a fixed effect model