I resuscitated this old post because there is still something which is not going like it should (IHMO).<br><br>$coeff without any extra-parameter between brackets&nbsp; is supposed to return a matrix, whereas actually, after an ols estimation with only one regressor, it returns a scalar instead of a matrix 1x1. Surprisingly (or not) if I try to access $coeff[1] it gives no error. <br>
<br>Moreover there is another issue connected somehow with $coeff and loops, but&nbsp; i couldn&#39;t&nbsp; replicate a minimal test-case.&nbsp; After the first iteration it&#39;s like $coeff weren&#39;t available anymore and any attempt to access to it produces an error:<br>
<br>&quot;The statistic you requested is not available&quot;.<br><br>Anyway I&#39;ll try to go deeper on this tomorrow, I&#39;m already sleepy..<br><br>Cheers,<br><br>Stefano<br><br><br><br>