In a video published online in September, a social scientist named Alex Spectre made an earnest pitch for his new startup. Clad in the Silicon Valley uniform of open-collar shirt and blazer, Spectre boasted that his company -- Philometrics -- would revolutionize the way online surveys were done, making it easier for companies to design questionnaires that people would actually respond to on Facebook, Twitter or other sites. Crucially, he said, the surveys could predict the responses for large...