Some parents dress up for Halloween. Some throw parties. In our house, we—well, I, really; my wife was bemused, my younger son vaguely interested, and my elder son embarrassed—I collect and chart the data.

First, the flow of trick-or-treaters. The figure below shows counts in 15-minute bins of kids who came to our door for candy. The first arrival, a little girl in a fairy/princess costume, showed up around 5:50 PM, well before sunset. The deluge came an hour later, when a mob from a party next door blended with an uptick in other arrivals. The other peak came almost an hour after that and probably had a much higher median age than the earlier one. The final handful strolled through around 8:40, right when we were shutting down so we could fetch and drop off our own teenage boys from other parts of town.

This year, I also tallied which candy the trick-or-treaters chose. The figure below plots the resulting data. If the line ends early, it means we ran out of that kind of candy. As my wife predicted, the kids’ taste is basically the inverse of ours, which, as one costumed adult chaperoning his child pointed out, is “perfect.”

To collect the data, I sat on my front porch in a beach chair with a notepad, greeted the arriving kids, asked them to pick one, and then jotted tick marks as they left. Colleague Ali Necamp suggested that I put the candies in separate containers to make it easier to track who took what; I did, and she was right. Only a couple of people asked me why the candies were laid out in bins, and I clearly heard one kid approaching the house ask, “Mommy, why is that man sitting on the porch?”