When I worked at Amazon.com they did analyze interviewing techniques, and I assume Google and other large companies do too. They didn't do controlled scientific experiments (as far as I know), but they looked at things like which phone screen questions were correlated with success in later on-site interviews, and did post-mortems of "wrong" interviewing decisions ("no" votes on someone who was eventually hired and successful, or "yes" votes on someone later found to be unsuitable). The data that comes out of this is not exactly scientific, but it does represent lessons learned from experience. [For what it's worth, a typical Amazon interview is a lot like a typical Google interview.]
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When I worked at Amazon.com they did analyze interviewing techniques, and I assume Google and other large companies do too. They didn't do controlled scientific experiments (as far as I know), but they looked at things like which phone screen questions were correlated with success in later on-site interviews, and did post-mortems of "wrong" interviewing decisions ("no" votes on someone who was eventually hired and successful, or "yes" votes on someone later found to be unsuitable). The data that comes out of this is not exactly scientific, but it does represent lessons learned from experience. [For what it's worth, a typical Amazon interview is a lot like a typical Google interview.]