[beder]

In that case, you should divide by "expected", so you get a percentage difference for each day. (Normalizing by total for the year doesn't make sense, since imagine that there were 300 days per month instead of 30 - your numbers would be divided by 10 again, but the data you want to visualize would stay the same.)

[rpicard]

I made an update using standard deviation and Z-score charts instead of my homebrew normalization function (see "Update"): http://robert.io/posts/4.html

[rpicard]

Great point! Dividing by expected would have been a much nicer solution. I think the method I used still works though, just not as nicely. Am I wrong?

[Kaizyn]

Z-Score is your friend for this kind of data normalization.

http://en.wikipedia.org/wiki/Standard_score

[rpicard]

Thanks. It looks like I need to do a little self-study in statistics.