David Gleich's Notebook

This afternoon, I added a "recent links" section to the left hand side of the main notebook index page.  This section tracks links from my delicious account.  After figuring out that I already had the Feeds App Lite plugin installed, it literally took about 5 minutes to get everything working.  From my perspective, that is simply awesome --- I didn't have to write a line of code!  Thanks to the authors of Movable Type and the Feeds App Lite for doing a great job.

Update It turns out Live Writer decided to change the quote setting to insert gnarly "curly" quotes instead of the standard straight quotes.  Ick, now I have to fix all these ugly quotes.  I'm not sure what isn't working now.

Many of my friends have birthdays in the next few weeks.  This fact prompted a discussion about the uniformity of birthdays.  In Outliers, Gladwell makes the case that birthdays of a group of individuals may appear skewed for subtle reasons; however such results shouldn't hold for the populace.

This question is easy to answer with a bit of Googling.  A Dartmouth professor has precisely the required data --- though only for a single year.

http://www.dartmouth.edu/~chance/teaching_aids/data/birthday.txt

I used R to make a quick display of the data.

No, that isn't a data problem.  There really are two groups of birthdays.

While looking for the overall date of birth data, I discovered another file from the CDC that explains the effect.

http://www.cdc.gov/nchs/data/statab/t941x16.pdf

The data in that file show many fewer births on weekends compared with weekdays.  This effect is precisely what we see in the plot, which R helps us validate.

This analysis was good enough for my own personal edification.  There is still a bit of work left to make these claims statistically valid, but that isn't my point here.