What should we conclude when the Adjusted R square decrease when adding a dummy variable into the regression?

[Phuc Nguyen]

In my regression using OLS, when I add a dummy variable into my regression, the Adjusted R-squared reduce from 0.6117 to 0.6111. Is it a critical result and what should I talk about the impact of adding this dummy variable.
Many thanks in advance.

[Felix Bittmann]

This is a very small change and probably without any relevance. I assume that your dummy is not significant (look at the p-value). I would simply say that your dummy is not able to explain variation in your outcome. But this also depends on what your exact question is so more context might be helpful.

[Carlo Lazzaro]

Phuc.
as an aside to Felix's helpful explanation, you can check yourself why, unlike R-sq, Adj-Rsq may decline when you plug in a new predictor in the right-hand side of your regression equation at https://stats.idre.ucla.edu/stata/ou...sion-analysis/.
As usual, you can get more helpful and faster replies if you post what you typed and what Stata gave you back (as per FAQ). Thanks.

[Phuc Nguyen]

Carlo Lazzaro and Felix Bittmann
Thank you for your reply, I cross-check the data and I got the answer.

Many thanks!