Paul Reilly has resigned as a member of comScore Inc.'s board after raising concerns regarding the company's operating strategy.

In a letter to the company's nonexecutive chairman, Brent Rosenthal, Reilly said he does not believe comScore's operating strategy is progressing fast enough, specifically in regards to innovation and product development.

Reilly was the chair of the board's audit committee and a member of the board's compensation committee, according to a Form 8-K filed Aug. 14.