There was also a difference by gender. Men were slightly more likely to say there was a hidden Trump vote and slightly less likely to say there was a hidden Clinton vote than were women. The difference was small: women were 5 percentage points more likely to say they strongly or somewhat agree with the idea that Clinton voters may be unwilling to state their support openly.
The university was generous enough to provide us with a breakdown by gender and party. (The sample size for independents was too small to be significant.) There, a wider gulf opens up.
Republican women were 8 percentage points more likely than Republican men to say that there is hidden support for Hillary Clinton. They were 5 percentage points more likely to say they felt that way strongly, and 3 percentage points more likely to say they felt it somewhat. Democratic women agreed with the idea more than Democratic men, too, though to a lesser degree.