I was working on some Time dependent data. Due to Client requirements I am forced to use LInear REgression for the modelling instead of Time series regression techniques like ARIMA. In order to not offend the Gods of data analysis, and also the Client, I was trying to cast a ARIMA model into a LInear Regression kind of framework. For that, I ended up including lagged values of the dependent variables (To imitate AR terms). End goal is to add terms so that the error terms are white noise.
Since what we have is not a text-book Linear Regression model, I had some concerns if Rsquare would be valid in such a situation. Could somebody please shed some light on the appropriateness of Rsquare in this situation of a Linear REgression with lagged dependent variable?