I have a regression prediction task where my outcome variable is right skewed. I performed a log transformation of the outcome variable and put it in a linear regression model. I assessed the R squared of the model and found it to be greatly improved (over non-transformed model).
Next I converted my dev set prediction values and dev set actual outcome values out of log scale (log -> exp). When I calculate R squared with the converted values it is quite a bit lower (.80 -> .70).
Am I wrong to think the R squared shouldn't be changing?