I am working on a OLS meta regression with a Willingness to Pay (WTP) variable as dependend variable. Since the values vary from small USD cent amounts to ~30 I want to use it in log form. Unfortunately, some WTP values are negative. I've read about the procedure of adding a constant so that all values are positive. I think this is the easiest way, but I am not sure if I can apply this on any data. I wonder if there is any other tool in stata 16 that can be used for that?
Additionally, do I need to transform also explanatory variables? I have some with monetary values, even though they are not directly influencing WTP, and several others, categorical and discrete.
Thanks in advance for your help!