I'm sure there's empirical evidence somewhere that can either confirm or deny this hypothesis, exactly as stated. But it's so valuable that Google isn't likely

I'm sure there's empirical evidence somewhere that can either confirm or deny this hypothesis, exactly as stated. But it's so valuable that Google isn't likely to give you a peek at it for free. Maybe some other market research firm will sell you related information. Or you could buy a few Google ads and see, I guess. Watch out for sample bias.