Tag Archives: estimates

Basic instinct for math?

It seems that there are two numbering systems in humans – a general sense of numbers for some quick and dirty estimates and some more genuine computation skills of showing the result of (2327)^2. At least the first capacity seems to be inborn (and an important survival skill). According a recent SZ article (29th Sept 2008) a host of new studies now show that

the two number systems, the bestial and celestial, may be profoundly related, an insight with potentially broad implications for math education

and as I believe – for science in general as most science fields are being dominated by the Fermi problem. Continue reading Basic instinct for math?

The winner’s curse

is another attempt to explain why replication fails frequently in genetic epidemiology. Zöllner and Pritchard write in the AJHG (their server is currently down)

For a variant that is genuinely—but weakly—associated with disease, there may be only low or moderate power to detect association. Hence, when there is a significant result, it may imply that the genotype counts of cases and controls are more different from each other than expected. Consequently, the estimates of effect size are biased upward. This effect, which is an example of the “winner’s curse” from economics depends strongly on the power of the initial test for association. If the power is high, most random draws from the distribution of genotype counts will result in a significant test for association; thus, the ascertainment effect is small. On the other hand, if the power is low, conditioning on a successful association scan will result in a big ascertainment effect.

I haven´t fully understood the following argumentation, but promise to revisit it some times later, yea, yea.