Wednesday, July 30, 2008

New CCP Metric: Lesson Efficiency

As you know, I like posting the numbers from the comic project's sessions, workshops, and modules. The numbers I usually list include the number of kids, the number of comics they made, and the averages.

I've recently thought of a new number that I'll be including from now on in future "stats" postings: efficiency. There will be two kinds of efficiency listed. The first is "student efficiency," which is the average comics made by each participant that I've already been listing.

The second type, which is new, is "lesson efficiency." This number will be a proportion of the total number of comics produced with the highest number that could have been collected given the number of participants.

For example, in a session I may give each child 4 warm-up comics and 3 activity comics to complete. So if I had 10 kids, I'd expect to get 70 comics total. However, not every child will finish every comic. Assume a couple kids get distracted and don't work on 5 comics, so I only collect 65. The session efficiency would then be 65/70, or 0.93.

Greater than 1.0 efficiency can be achieved through the production of original comics, which aren't usually planned ahead of time. So in the above example, if I collected 65 comics from the 70 expected, but also received 20 original comics, the efficiency would be 85/70, or 1.21.

The purpose of this number is to allow me to compare various sessions with a number that controls for things like the number of kids and the number of comics made available to them, since these numbers vary widely between sessions. In other words, this allows me to control for the natural link between number of kids and the number of comics produced and see how well the kids are completing the lesson in the time allotted.

A low efficiency means I gave them too much work or didn't instruct them well enough, a high efficiency means they were able to complete everything as planned. The efficiency score is vulnerable to downward bias in cases where kids complete comics but take them home, i.e. when comics aren't collected. The 12/29/07 Workshop was a prime example of this bias at work.

For some lessons, such as modules where participation is defined by comic completion or sessions with no expected number of comic production, the efficiency score will be inapplicable, but it can be defined for most of the lessons I've done so far. Expect a future post where I'll go through and measure the lesson efficiencies for several past sessions/workshops/modules.

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