Why do PhD admission committees focus on your bachelor's degree grades when you have better master's degree grades?
In the U.S. and in math, at least in my experience, graduate grades tend to be less reliable measures than undergraduate grades for how one did in a class. Graduate grades tend to be A -- &quot;good&quot; to &quot;excellent&quot;, B -- &quot;total-incompetence-but-attended-class&quot; to &quot;acceptable&quot;, C -- essentially you failed (for some programs, you're gone if you accumulate 3 C's).
Universities and departments range from &quot;B's are rarely given and C's are almost never given&quot; to &quot;A's tend to be given for work consistent with passing the Ph.D. qualifying exam in the subject&quot;, B's tend to be &quot;not horrible&quot; to &quot;good-but-not-exhibiting-future-Ph.D.-potential-performance&quot;, and perhaps a few C's are given for especially bad work.
Nonetheless, I would think nearly all A's and well above average recommendations in a Masters program would undo all but the very worst of undergraduate grades, and maybe even those. But a 3.3 Masters average and typical-good-sounding recommendations are not going to undo a 2.8 undergraduate average in one's major.