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Even if the sequencing process has very high accuracy, the conditional probability these people having the genes but not disorders could be low. By Bayes Rule:
by oli5679 11y ago
Even if the sequencing process has very high accuracy, the conditional probability these people having the genes but not disorders could be low.
By Bayes Rule:
PR(Gene & no disorder | disorder result) =
Pr(disorder result | gene & no disorder) * Pr(gene & no disorder)
/ Pr(disorder result | gene & no disorder) * Pr(gene & no disorder) + Pr(disorder result | no gene & no disorder) * Pr(no gene & no disorder)
Even if the test is incredibly accurate and so Pr(disorder result) is much higher for people with the gene, this may be outweighed by the relative likelihood of having the disorder given you have the gene (this could plausibily be 1!), making the conditional probability very low.
- pingou 11y agoBut will the test always give a false positive for some people or is it usually more random? If it is, then just test the sequences again.
- oli5679 11y agoYeah, if you have tests without strong correlations then your approach is a good one. My point is that when your test returns a result which had low prior probability (even if the test is accurate) you should often retain a lot of your scepticism. In this context, it may well be that many of the people identified didn't have the genetic disorders indicated...