Rule-of-thumb suggested by Green(1991)(https://doi.org/10.1207/s15327906mbr2603_7) : "Some support was obtained for a rule-of-thumb that $N ≥ 50 + 8 m $ for the multiple correlation and $N ≥104 + m$ for the partial correlation."
I would like to determine the upper limit of the number of covariates $(m)$ according to the rule-of-thumb suggested by Green in an analysis using a general linear model with a fixed sample size $N$. The purpose is to verify the statistical significance of the regression coefficient of a predictor after controlling for the effects of several covariates.
In this case, which formula is appropriate for the model? $N ≥ 50 + 8 m$ or $N ≥104 + m$?