deodands

Perpetual student

[My friend RL is nearly at the end of a pureish maths degree and is considering a physics one and an applied maths MSc]

There is something to be said for acquiring lots of human knowledge by doing degree after degree. But not that much.

Acquire one degree and you demonstrate (partly to others but mostly to yourself) that you have all the skills and talent to find, judge, and use for your purposes the kinds of knowledge that you need to solve problems and follow your interests. While there are big, big, cultural differences, a pure maths degree is your self-certification that you can potentially learn all the undergraduate maths, physics, compsci and actually quite a lot of other sciences if you ever need to. Of course learning more and more of them through a formal degree is great (just wait till you get to molecular biology, which blows the rest away...) but there are some opportunity costs.

One cost is that an extra cognate degree adds practically no market value to you. Going off and doing a law degree or a psychology one or English or something would do, and certainly gives you a whole different set of skills which I have learned to value through their absence.

But the biggest opportunity cost is that learning anything is not the same as doing it. For some people that matters because they love the doing of it, and those people certainly report such a high from that doing that it is worth a try. As for me, I never really inhaled. What I loved about becoming an academic was the extra insight it gives you into what human academic knowledge means. I had some papers I was proud of but I think I was most proud of the fact I could ask sensible questions about other people's papers. The trade of getting a PhD written, papers out, and then getting and delivering grants gives you a critical, tired eye for the mass of dullness people will claim your attention for. And that makes your appreciation of the little nuggets of wonderfulness about the human potential for understanding, like the solved extracellular structure of the EGF receptor or PageRank or vector spaces, all the keener.

Find an area you love and dive into a PhD. You'll end up despising most of what you thought you loved, but unlike most human relationships that makes what's left over all the sweeter, and unlike all human relationships it is guaranteed to stay with you until death.

Times drops signal, shows noise

A Times story about Waitrose being worst at selling alcohol to minors.

Findings from an alcohol enforcement campaign suggested that Waitrose had the worst record for selling alcohol to under-18s, followed by Somerfield and the Co-op.

Waitrose sold alcohol in 22 per cent of cases where trading standards officers used under-18s in secret test purchases. The other big chains similarly tested were Somerfield (20 per cent) the Co-op (17 per cent), Tesco and Sainsbury (both 16 per cent) and Morrisons (15 per cent).

To be fair on Waitrose staff, they were probably so shocked to see anyone who looked under 18 walking around the most expensive supermarket chain in the country that they forgot to ask.

A rather better way to be fair to Waitrose staff might be to observe the likely uselessness of those numbers to support this conclusion. Think about opinion polls - carefully sampled, typically several thousand respondents, and they still report a sampling error of +/- 3%. Journalists are not in general good at pausing to consider how much numerical difference is likely to be attributable to noise and the Times ones are apparently no exception. In fact the only time one routinely sees uncertainty estimates and sample sizes is in those opinion poll reports, presumably because people subsequently remember when newspapers call elections wrongly.

A little digging on the Home Office site reveals firstly that the journalists have factually misreported - there was, contrary to their claim, another supermarket involved, Asda down at 7%, much more of an outlier than Waitrose.
Secondly it hints at a sample size by discovering that there were nearly 600 charges as a result (a rather large sample: obviously the police are finally discovering the true meaning of power). Across seven supermarkets, one of which is small and regional (until Waitrose Wilmslow some of us Northern affluent, young, urban consumers have been guiltily supplied by Ocado from, yes , Stevenage...) its unlikely that more than 50 were from Waitrose, so about 250 trials maybe. Estimating .22% from 250 trials gives
you what the opinion pollsters would call a range of error of about +/- 5% (ie the 95% confidence interval for the true population parameter in 250 binomial trials with 55 successes is 17.02-27.65%).

A third observation is that all of these differences are dwarfed by the massive difference observed between the trials
done last summer (nearly half of all underage purchases unchallenged) and last month. Since the Home Office press release explicitly mentioned this, the Times must have consciously chosen to neglect this, probably meaningful difference, in favour of a probably meaningless one dissing Waitrose. They probably know their readership goes to Sainsburys (scroll to the bottom, pausing to marvel at Asda.)