Badgett and other scholars point out a number of reasons these figures aren't comparable.

WSJ: Gay Divorce Rate Proves Hard to Measure

During the trial, Mr. Egan and Ms. Badgett discussed the difficulty of quantifying the broader economic effects of banning gay marriage.

WSJ: Cost of California Gay-Marriage Ban Unclear

Mr. Egan and Ms. Badgett were called to testify by the San Francisco City Attorney's Office and lawyers David Boies and Theodore Olson, who are seeking to overturn Proposition 8.

WSJ: Cost of California Gay-Marriage Ban Unclear