Hello!

When testing the normality of the residuals of a multiple regression by OLS, I found that these are not normal. I tried to perform a correction by Box-cox on the dependent through the command bcskew0. However, no conversion is performed.

I tried the general command by: boxcox btdt var_rec var_inv lagbtdt, lrtest , but the error appeared:
btdt contains observations that are not strictly positive
r(411);


[P] error . . . . . . . . . . . . . . . . . . . . . . . . Return code 411
nonpositive values encountered
__________ has negative values
time variable has negative values
For instance, you have used graph with the xlog or ylog options,
requesting log scales, and yet some of the data or the labeling
you specified is negative or zero.
Or perhaps you were using ltable and specified a time variable
that has negative values.

(end of search)
The independent variable is continuous, and in fact, has negative values.
My question is: is it not possible to box-cox variables that have negative values? What would be the problem I am facing with my database?

Help me please!