In November 2016, I attended the A2 Data Dive, a data analysis event hosted by the University of Michigan School of Information. Several nonprofits shared their data with us and we all took different routes in analyzing it. The group I was in worked with the Salem-South Lyon District Library. Some people converted paper records of attendance to see what days and times were the busiest. I chose to compare Salem-South Lyon to other libraries across Michigan.
The trendline shows that there is one computer added for every 1,111 people served by the library. Here’s a more detailed view with the library highlighted.
The difference in population served between small libraries is quite small: between the 9th and 10th smallest, the difference is 223. As you move up to the bigger libraries, the gaps become bigger: between the 9th and 10th largest, the difference is 10,293. Zipf’s law for cities represents this pretty well. The 4th biggest city will be 1/4 the size of the biggest city, the 10 biggest will be 1/10 the size of the biggest, etc.
Out of the 392 libraries in Michigan in the data set, Salem-South Lyon ranks 5th in circulation per capita, which is how many items an average person in the library’s area checks out per year.
They rank 12th in circulation per cardholder at 35.2 items a year.
The material turnover rate was 3.3. This means an average item was checked out 3.3 times a year.
This library stood out in several other categories. There were 10.2 visits per capita, ranking 29th in Michigan. Average annual uses of library computers per capita was 5.4, which is 3rd. Annual Wireless Internet Logins per capita was 3.3, which is 9th. Operating income per capita was $91, which is 13th.
This last stat wasn’t an actual category in the data, but there was total hours worked by paid staff, and number of visits, so I made it. For every visit, paid employees worked 7.13 minutes, which ranks 177th.