The error "factor-variable and time-series operators not allowed" when running xi: mixed command

[Sarah Yeo]

I wanted to see the interaction and used the command below and got the error message (factor-variable and time-series operators not allowed
r(101)


xi: mixed base_toi i.treat*i.time*i.riskgrp || id: , cov(exch) reml

Any kind suggestions to improve the command?

[Richard Williams]

Unless you've got an ancient version of Stata, you shouldn't be using xi:. Use factor variable notation. See

help factor variables

I think the equivalent command is something like

mixed base_toi i.treat##i.time##i.riskgrp || id: , cov(exch) reml

[Sarah Yeo]

Thank you so much Richard!