Here’s a link to the story about the study, which implies that women critics are outnumbered and that since women critics are more likely to review films made by or about women (there’s an observation that surprised me. I thought we all reviewed whatever came down the pike, no matter who made it), this could hurt female filmmakers and “chick pictures,” or movies aimed at a female audience.
Not exactly an exhaustive study, simply focusing on Rotten Tomatoes critics. Most of us are there, and they’re a bit arbitrary on how they place you and who they call “top critic.”