<p>
</p>
<p>Again, you miss the whole point of Berkson’s example. He assumed that there was no relationship between hypertension and skin cancer, that is, properly implemented studies should not find a link between the two. But he showed that a relationship could easily be found in seemingly scientifically controlled case-control studies as long as hospitalization rates among the three groups to be studied differed. That relationship arised purely because of statistics; by assumption, it did not exist in the general population, but statistically, it had to exist in the study.</p>
<p>It’s the same thing here. There is no relationship between being Asian and talent in the general population. But given our assumed relationship between the SAT score and talent / effort, we can easily show that since on average, Asians prep more (i.e. have higher values of effort than non-Asians), they will necessarily have lower values of talent (than non-Asians), for any given SAT score.</p>
<p>Arithmetically, that has to be true. But what are the implications, beyond using Asians polemically? Under your policy prescription of “meritocratic discounting,” if a college has any reason to suspect that applicant i with SAT score 750 has a high value of effort, then given our assumed relationship, he must have a low value of talent, regardless of racial classification. For example, if we believe that wealthy students can put in more effort than non-wealthy students due to being able to afford test prep both in nominal costs and opportunity costs (i.e. they do not have to work part-time jobs to support their families), then given our assumed relationship, colleges should estimate the talent of wealthy applicants as lower than that of non-wealthy applicants, for any given SAT score.</p>
<p>The correlation must hold true for any given SAT score and given our assumed relationship between the score and talent / effort. But, again, does anyone actually believe that? </p>
<p>
</p>
<p>Let’s go back to [Murphy’s</a> example](<a href=“http://www.cs.ubc.ca/~murphyk/Bayes/bnintro.html]Murphy’s”>Graphical Models). He let C denote the event that someone is admitted to college, which is true if someone is either brainy (B) or sporty (S). In the general population, B and S are (statistically) independent. If we restrict our attention to a population of college students (C is true), then it can easily be shown that being brainy is negatively correlated with being sporty and vice versa. Why? Either property alone is sufficient to explain the evidence on C; the two “compete” to “explain” C.</p>
<p>Now, let C denote the event that someone has an SAT score of 750. To simplify the correspondence, let E and T be binary variables where a value of 1 indicates high effort or high talent, respectively, while a value of 0 indicates low effort or low talent, respectively. C is true if someone is either high effort (E) or high talent (T). In the general population, E and T are (statistically) independent. If we restrict our attention to a population of students who have earned an SAT score of 750 (C is true), then again, we can show that having high effort makes an applicant less likely to have high talent and vice versa. Why? Either property alone is sufficient to explain the evidence on C; the two “compete” to “explain” C.</p>
<p>Again, when we restrict our attention to situations where C is true, two independent variables BECOME dependent because of statistics. They “compete” to “explain” C, and so if one goes up, the other goes down. That’s all. To argue for “meritocratic discounting” based on a “one goes up, the other goes down” relationship that arises because we have restricted our attention to certain events is quite absurd.</p>