(Section 8.3)
Some of the days have significantly fewer births. What’s going on?
There are fewer births on weekends!
This new variable says whether or not a day is at the end of the week:
wday month day_of_month
2 Mon 1 2
149 Mon 5 29
185 Tue 7 4
247 Mon 9 4
327 Thu 11 23
359 Mon 12 25
They are all major holidays!