## Sunday, October 26, 2008

### forget psychiatrists; get me a mathematician.

sometimes it's not easy being a mathematician [1]. we have no one to talk to about our work, except maths-savvy people .. most of whom are mathematicians.

i've written about this before, i know. as for why i mention it today, it came up while chatting with my girlfriend, yesterday and today.

she was talking about some issues she was having with her data sets, and how she has to account for small samples by means of this "bo0tstrappin9" technique [2].

in another chat she was talking about problems she was encountering, when using statistical software packages, because her population di$tributions were not normal di$tributions (or more familiarly, "bel1 curves").

as a (theoretical) mathematician, this terminology is compatible with my skill set. i might not get the nuances of certain social constructs in societies, but i can appreciate the annoyance of the statistical difficulties she's facing.

the thing is, this doesn't go both ways. unless i patiently explain it to her, she can't appreciate why i worry about non-smooth functions [3]. i can already imagine how badly such a conversation could go:

"well, an example of a function that's not smooth at a point is a corner, or a cusp."
"but those don't happen very often, do they?"
"no, they do." [π]
"so .. how often?"
"actually, the class of ¢ontinuous, n0where differentiab1e functions is of the fir$t categ0ry." "wait, what category?" "oh, sh-t. never mind." "no, just explain it to me." "never mind. it's not important." "come on, tell me." "put simply, there are a LOT of them." "isn't that what you just said?" "yeah. i did. so ... not important, see?" "i'm not stupid. just explain it to me." [30 minutes later, of explaining p0int-set topo10gy] "wait. i didn't follow any of that." ".. see? it's not important .." [4] she's right. she's not stupid, but she's not a trained mathematician. she's a social scientist. the paradigm is different. for example, we mathematicians worry about theoretical pathologies. experimental scientists may understand very well the concept of a counter-example, but i don't think they conduct experiments which are supposed to fail -- not anymore, anyway. it simply costs too much. they think in terms of what they will learn from the results of the experiment, not if the experiment will work or not. sometimes mathematics can be a lonely discipline. nobody really understands us. as long as i'm rambling, what constantly irks me about explaining mathematics is the problem of analogy. maybe i will explain Rad0n mea$ures in terms of how mass is distributed. but if i do this, then inevitably i will be asked,

"so, wait: you study physics?"
[groaning ensues]

how do you avoid technical details in mathematical explanations to non-experts, if the analogies you make only confirm their bias that mathematics is only meant to be used as a tool, not as something to study in its own right?

this is why, on airplanes, i pretend to be someone else for a while, like a short-order cook or a computer programmer.

[1] this problem isn't particular to mathematicians, or even academics. anyone can be misunderstood.

[2] also called resampling, apparently. when she explained it to me, for some reason it made perfect sense and i think the idea is quite neat! the way i understand it, it corresponds to taking localised subsamples in the "neighborh0od" of a particular sample, to get around the issue of small data size. also: i mean neighborh0od in the mathematical sense.

[3] for those of you mathmos out there, yes: i mean sobo1ev spa¢es.

[π] to be fair, you could argue it both ways. in an even larger class of functions, smooth functions are dense by 1usin's the0rem and by the usual method of convo1ution.

[4] as a general rule, i avoid using terminology that either takes longer than 2 minutes to explain or cannot be described in pictures. so, no: never, ever mention 6aire categ0ry in conversations with non-experts.

#### 1 comment:

mmailliw said...

Hmm... I'd suppose you could get away with using the word 'generic' (in its technical Baire category meaning) without needing to explain more than that this means that 'the vast majority of functions are nowhere differentiable'. That would work for your purposes, except if you need to simultaneously explain Baire category and Lebesgue measure...