## Monday, February 4, 2013

### Why it's been a while, and will be a while longer

 Hannah, a lovely distraction born December 20, 2012 - here 6 weeks old
In case anyone is wondering, the longer-than-usual gap between posts is due to the above tiny but huge bundle of joy. I'm on parental leave from work until August this year, and am too busy with baby to think or write about teaching.

Although... while I was still pregnant and teaching, I realized that pregnancy and child-rearing presents the curious parent with lots of authentic mathematical questions of varying complexity and difficulty. Here are some preliminary notes on ideas:

• What are the chances of getting pregnant? Contraceptive technology offers a summary table, which informs us about how many women per year, using each of the methods, gets pregnant. How do we translate that into risk of pregnancy per "occasion"?
• What are the chances of getting pregnant when one tries? This somewhat depressing graph implies that the chances decrease for each month one is trying, but why? And isn't there a problem with the graph?
• Miscarriage is such an ugly word, but let's face it: most pregnant women worry at some point or other about whether they'll get to keep the baby. Data on spontaneous abortion (not any less ugly) naturally leads to a discussion about conditional probability, wikipedia has some interesting numbers to work with under the subheading epidemiology. There's also this great example of a function of several variables (maternal and paternal age).
• Once pregnant, when will the baby be born? This site has statistical table and graphs for the distribution and cumulative distribution for births after 35 weeks, and can be used to investigate questions of conditional probability ("If you're already at 39 weeks, what are the chances the baby will be born within the next week?") as well as cumulative frequency, probability distributions, normal distribution (although it's more likely to be log-normal, but oh well...) and many other topics within probability and statistics. For fun, one could also check and discuss any discrepancies between the answers arrived at in class and the numbers of the complete statistical table here.
• How do babies grow before and after birth? From the stats on students could practice creating normal distributions for weight, length, and other values and thereby gain more familiarity with multiple representations involving the normal (log-normal) distribution. WHO offers growth charts used by health professionals world-wide, andBBC page discusses their usefulness and why they needed to be updated.
There is lots more that can be done with pregnancy and baby health and growth data (for example the birthday problem!), and I think I would be able to form an entire unit on probability and descriptive and inferential statistics based on such data. While not all students will be intrinsically interested in this application, it does seem likely that many will find the experience useful some time in the future.

Right, little mewing noises from the bedroom let me know that time's up.
Have a great time teaching, everyone!