做DDD,如下代码,报错maxvar too small
reghdfe lev Treat_y2003_highind Treat_y2004_highind Treat_y2006_highind Treat_y2007_highind Treat_y2008_highind i.ind_year i.prov_year i.ind_prov, cluster(coid) absorb(coid)
报错:
maxvar too small
You have attempted to use an interaction with too many levels or attempted to fit a model with too many variables. You need to
increase maxvar; it is currently 5000. Use set maxvar; see help maxvar.
If you are using factor variables and included an interaction that has lots of missing cells, try set emptycells drop to reduce the
required matrix size; see help set emptycells.
If you are using factor variables, you might have accidentally treated a continuous variable as a categorical, resulting in lots of
categories. Use the c. operator on such variables.
r(907);