Consider the model with a single regressor. This model also can be written as

Yit $=$ b$0+$ b$1$X$1,$it $+$ d$2$B$2$t $+$ g $+$ dT BTt $+$ g$2$D$2$i $+$ g $+$ gn Dn i $+$ u it$,$

where B$2$t $=1$ if t $=2$ and $0$ otherwise, D$2$i $=1$ if i $=2$ and $0$ otherwise, and

so forth. How are the coefficients $1$b$0,$ d$2,$ c$,$ dT$,$ g$2,$ c$,$ gn$2$ related to the

coefficients $1$a$1,$ c$,$ an$,$ l$1,$ c$,$ lT$2$