Today’s post over at I.N.K. would be a great one for introducing your kids to reading critically. Or even for reflecting on some of the issues of presentation yourself. I want to explore those links to Tufte’s work more, both on that question and on presenting statistical data.
I used to do a couple of sessions with my sociology of the family students on the presentation of statistics about marriage and family in the media. UK statistics almost always show a graph beginning in 1971. Marriage rates decline on a pretty steep curve from there. I would ask students to talk about how they visually extend that line in their heads (mostly we assume it keeps going the same way in both directions) and then point out that 1971 was the highest ever rate of marriage in the UK. So if you actually extend it, that top point in the graph they show is really the peak of a mountain. I would then show them superimposed graphs from previous historical periods, demonstrating that current rates of marriage, marriage dissolution (if you combine death and divorce), length of marriage, etc are very similar to those over 100 years previously.
Of course, when talking about marriage and family data, you also have to discuss cohort effects. A big chunk of the apparent decline in rates of first marriage is due to increasing age at first marriage (the early 1970s was also when age at first marriage was at its lowest in the UK). So that some of those not married are just not married yet. But that story is kind of complicated and doesn’t make anywhere near as interesting a story as the kind of moral panic you can create with a nice steep line on a graph.