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By using the prior admissions test scores you are assuming that those factors are relevant to a population that has graduated and passed your own screening. Un
by yummyfajitas 10y ago
By using the prior admissions test scores you are assuming that those factors are relevant to a population that has graduated and passed your own screening.
Unless applying your screening to a population somehow magically eliminates all variation that previously existed across the populations, that's a perfectly valid assumption.
The argument that if the prior is wrong, it hurts you is of course true. Similarly a uniform prior in a non-uniform situation will hurt you - see this example for an illustration of how ignoring base rates can spread HIV. https://www.chrisstucchio.com/blog/2016/why_gays_cant_donate_blood.html https://www.chrisstucchio.com/blog/2016/why_gays_cant_donate...
- hackinthebochs 10y agoThe difference in the HIV case is that we have an actual population sample that justifies our chosen base rate. That is to say, this isn't a "prior belief", this is a measured statistic. It's applicability is precisely because the population of individuals getting an HIV test is random from the general population, from which we have a measured statistic. But the use of the base rate in this case does not justify the usage of informative priors in every case. >Unless applying your screening to a population somehow magically eliminates all variation that previously existed across the populations But it might. The "population" of graduated + passed screening bears no a priori relationship to the population of entering freshmen precisely because this is a non-random sample, orders of magnitude smaller than the original population. Furthermore, there is further evidence that there is no relationship precisely because of the studies that show that entrance exams bare little correlation to college success past the first year.