# blueollie

## A bit of statistics

Ok, how can we draw statistical inference when we cannot run a controlled experiments? After all, correlation and causation are not the same. This is a useful guide as to the how and when. Basically: is the correlation strong, and is there some “plausible reason” for such a correlation? This paper lists 7 points.

Simpson’s paradox You can see a discussion here.

Think of it this way: say 1000 women and 1000 men apply for admission to graduate school. 656 men get admitted, whereas only 260 women get admitted. Does this mean that things are biased against women?

But then we see that there are two very different graduate programs. The very selective graduate program admitted 8 percent of all male applicants but 10 percent of all women applicants. The other graduate program..the “easy to get into” program admitted 90 percent of female applicants and 80 percent of all male applicants. So: we see that the women outdid the men in both programs. Yet, we also see that 800 women applied to the “difficult to get into program” and only 200 men did. On the other hand, 800 men applied to the easy program but only 200 women did.

Check it out: women: 800*.1 =80 admits to the hard program, 200*.9 = 180 admits to the easy program, so 260 total admits. Men: 200*.08 = 16 admits to the hard program, 800*.8 = 640 admits to the easy program, or 656 total admits.

This isn’t just some “trick” either. When social scientists analysed the “stand your ground” defense law in Florida, they found that whites were more likely to be convicted than non-whites. BUT this was because whites were more likely to be accused of assaulting a white victim; it turns out that the probability of prosecution was higher if the victim was white than if the victim was non-white. You can see the details here.

workout notes: 4 mile walk after weights: rotator cuff, 5 sets of 10 pull ups, bench press: 10 x 135, 5 x 185 (strong), 10 x 170, incline: 10 x 135 (very easy), military: 10 x 50 standing, 20 x 50 seated supported, 10 x 200 machine, rows: 3 sets of 10 x 50 single arm. head stand, 2 sets each of 10 yoga leg lifts, 12 twist crunch.