Needs a diff-in-diff

I'd love to see somebody else head into the Stats Datalab and do a bit more digging into recent declines in teenage fertility rates.

Teen fertility rates are down but we aren't entirely sure why. The new report commissioned by the Social Policy Evaluation and Research Unit notes increased use of contraception but doesn't have any clear reason why contraception use has increased. They note the link between deprivation and higher birth rates; it would be interesting if they presented results sorted by income cohort.

The time path has a sharp drop from the 1970s through the early 80s, then a slow decline, then a sharp rise from '05 to '08, then a reasonable decline since '08.

I wonder whether changes under National restricting the generosity of benefits paid to single mothers who have an additional child while on benefit have had an effect on teen birth rates.

Somebody with DataLab access could check:

• differential effects on teenage fertility of the changes to benefits by comparing cohorts likely to access benefits conditional on childbirth with higher-income cohorts unlikely to do so;
• differential effects of easier morning-after pill access in Auckland, later rolled out to other cities, as compared to regions where it's more difficult to access pharmacies;

Please go and make this your thesis and report back.