Doing the quintiles, part 1: Posting frequency

As noted in *Public Library Blogs: 252 Examples*, the 252 blogs studied had a total of 5,976 posts during the study period (March 1, 2007 through May 31, 2007: 92 days). That’s an average (mean) of 23.7 posts per blog, or about one every 3.9 days–which I called “a bit less than two posts per week.” The median was considerably lower: 12 posts, or a little less than one per week.

Here are the quintile figures. I needed to account for the two extra blogs (5 into 252 leaves a remainder of 2), and as it happens there were 52 blogs with fewer than 16 and more than 9 posts, so I included the extras in the middle quintile.

- Q1:
**Most posts:**From 33 posts (one every 2.8 days) to 400 (4.3 per day).

**Average**: 73.9 (four posts every five days)

**Median**: 58 (one post every 1.6 days).

This quintile accounts for**61.8%**of all posts. - Q2:
**More posts**: From 16 posts (roughly one every six days) to 32 (one every 2.9 days).

**Average**: 22.5 (roughly one post every four days)

**Median**: 22 (same)

This quintile accounts for**18.84%**of all posts. - Q3:
**Average frequency**: From ten posts (one every nine days) to 15 (one every six days)

**Average**: 12.2 (just under one per week)

**Median**: 12 (same)

This quintile accounts for**10.61%**of all posts. - Q4:
**Fewer posts**: From five posts (one every 18 days) to nine (one every ten days).

**Average**: 7.06 (one every thirteen days).

**Median**: 7 (same).

This quintile accounts for**5.91%**of all posts. - Q5:
**Fewest posts:**From two posts (one every 46 days) to five (one every 18 days)–noting that 15 blogs had five posts each, making it impossible to break quintiles at a number break.

**Average**: 3.38 posts (just over one per month)

**Median**: 3 (one per month).

This quintile accounts for**2.83%**of all posts.

It’s worth noting that Q5 hits the lower limit of the study:**Blogs with one post were excluded**.

In an extreme case, if you took a sample of 50 public library blogs and happened to get all blogs from Q1, and then took another sample and happened to get all blogs from Q5, you’d have a truly ridiculous situation: One group would show more than **twenty times **as many posts as the other group!

With a distribution like this, it’s interesting to see how closely it approaches the Pareto assumption. The answer: Not very. To get 80% of the posts, you need to include 38% of the blogs.