在'对比<- ' ' (' *tmp* '， value = contr.funs[1 + isOF[nn]])中出现的错误:对比可以只适用于两个或两个以上级别的因素。

I have the following code for minimizing the sum of deviation using optim() to find beta0 and beta1 but I am receiving the following errors I am not sure what I am doing wrong:I have the following code for minimizing the su