when random sample is used in regression what does randomly random sample mean if sample for cross section is random in panel regression, what can i do why is the cross section random in panel regression what is the sample for panel regression if a cross section sample is random what do i do what if the cross section sample is random what happens when sample for cross section is random what is the difference between fixed and random effects in regression? what if a sample for crossover is not random in the test when the sample is random in a regression model what to do if the sample is randomly drawn in a regression model? what is the difference between variable random and fixed effect? what do you do if the sample for cross section is not random why is cross section sampling in panel regression what to do if cross section samples are not random what to do when cross section in regression analysis what can happen if random sampling is used in a panel regression what to do if sample is random what to do if the sample is not randomly populated