The “Richards effect” is the phenomenon in which polls consistently underestimate support for female candidates relative to white male candidates.
The termed was coined by political scientists Christopher Stout and Reuben Kline who noted that in the 1990 Texas gubernatorial race many polls predicted Clayton Williams (R) to beat Ann Richards (D) by as much as 8 points. However, Clayton’s “lead” evaporated on election day and Richards won.
From their research paper: “Perhaps it was not only the traditional polling problems that led polls to be less accurate, Ann Richards’ gender may have also played a vital role in these polling discrepancies. Our results indicate that female candidates, and in particular female candidates from gender-conservative states, like Ann Richards in Texas, tend to do worse in pre-election polls than in actual elections.”