Assessed , Absent , Excluded , Ineligible , Not in sample-Other reason , Not in sample-dropped replacement (participating original school) , Not in sample-dropped replacement (participating replacement) , Not in sample-dropped replacement (for ineligible school) , Not in sample-dropped replacement (for excluded school) , Not in sample-dropped original that can't be counted towards response rates but replacement could count , Not in sample-school with <25% student participation, other than those that fit the particular W_STUSTAT=95 situation , Not in sample-should have been an excluded school with only 1 or 2 PISA students , Not in sample-school exclusion because all students are excluded , Not in sample-school ineligible because all students are ineligible , 1