## Journos: Back to stats 101!

The other day, a (rather clever) student told me that she has no real need for all these stats classes, because she will be a journalist. I told her that the world would be a better place if all journalists underwent compulsory numeracy classes. Here is the proof from my favourite newspaper. How long does it take you to spot the glitch?

Young people in the East Midlands were the most down-to-earth of those surveyed, expecting an annual salary of £33,468 by the time they reached their mid-thirties. However, even this figure is still around £4,000 higher than the average.

Two-thirds of respondents also thought they would own a house by the time they were 25. In reality, only 14% of homeowners are aged 25 or under.

With the rising cost of higher education hitting students hard, recent figures suggest young people will be left with more than £20,000 of debt by the end of their courses. But the poll shows today’s school children do not realise how out of pocket they will actually be: the average expected figure was just half the reality.

http://www.guardian.co.uk/money/2010/mar/30/teenagers-expect-earnings-51000

## All singing, all dancing 3d function plots with beamer, pgfplots and animate.sty

I use emacs/$LaTeX$for all my textprocessing needs, and for the last four or five years, I have created all my slides with Till Tantaus excellent “beamer” class. At the moment, I’m teaching a 2nd year stats course (imagine doing this with PowerPoint – the horror! the horror!), so I sometimes use graphs from the assigned text like this one from Long&Freese that illustrates the latent variable/threshold interpretation of the binary logit model. The message should be fairly clear: $y^{*}$ depends on $x$ andfollows a standard logistic distribution around its conditional mean.

But the fact that the bell-curve lies flat in the $x-y^{*}$ plane confused my students no end. So I wasted half a day on creating a nice 3d-plot for them. After trying several options, I settled on pgfplots.sty, which builds on tikz/pgf, the comprehensive, portable graphics package designed by Tantau (here’s a gallery with most amazing examples of what you can do with this little gem). Plotting data and functions with pgfplots in 2d or 3d is a snap, so that was not too hard. Eventually.

Finally, in a desperate attempt to drive the message home, I enlisted the help of animate.sty, yet another amazing package that creates a javascript-based inline animation from my $LaTeX$ source (requires Acrobat reader). So the bell-curves pop out of the plane, in slow motion. Did it help the students to see the light? I have no idea. Here is the source.