I am trying to interpret a non-linear relationship in a fixed effects model. Attached is my Stata output. As you can see from the output, both the overhead ratio and the overhead ratio squared are positive and significant.

However, when I graph the predicted values I get a u-shape relationship and when I do a margins plot I get an inverted-u. So I'm not sure which is accurate? I also thought that if a non linear relationship is present that one value would be negative and the other value would be positive.

Any help would be much appreciated!