Derivation
variable: plotscore (table[s]: this dataset)
variable: harvestscore (table[s]: this dataset)
variable: harvsellscore (table[s]: this dataset)
egen agriscore=rowmean(plotscore harvestscore harvsellscore) if plotscore~=. & harvestscore~=. & harvsellscore~=. /*combined agriculture score is average of all 3 scores*/