The Whiteboard

A couple of weeks ago, Ed bought a whiteboard for our apartment ($8 at Walmart). He already had a tripod-style easel that his mom gave him, so this easel-mounted whiteboard now lives in his room. The idea was to make it easier for us to show each other things, and also as a general math-working space for him (I think).

Last night, quite late, he was eating dinner and I wanted to show him the smallest finite projective plane (the Fano Plane). It's really hard to show someone something on paper, because you just can't write on paper while holding it such that the other person can see it, at least not easily. This is doubly true if the person is trying to eat a plate of pasta at the same time.

"Want to use the whiteboard?" he asked.

It was our first time to try it together. He got to chill out sitting on his bed with the pasta while I drew and explained the plane (shown at left). And it was awesome.

I wasn't that into having a whiteboard, but now I can't see how we could live without it.

Advantages of a Log Scale

One option that Excel has, and that I imagine most graphing software has, is to convert one of the scales from the regular linear scale to a logarithmic one. In a logarithmic scale, the equally-spaced intervals represent powers of 10.

In the oil industry, we use log scale charts quite a lot, and they often make the data more sensical. Today I made the following scatter plot, which shows the oil to gas ratio for some wells in Oklahoma. The x axis represents how long the well has been running, so the idea is to see how these ratios might change over time, and how they vary from well to well. It came out like this (get a bigger image by clicking):
This is obviously not acceptable as a graph. The couple of really high values near the top edge make all of the more normal values clump together at the very bottom. And no matter how much I limit the range of the y axis, I get basically the same effect. Here I've limited it to 2000, which cuts off some data points:

It's better, but it's still not great. Then I tried a log scale:

And voila. Suddenly this data makes sense.

Log scales are a bit tricky for people to read, so it does help to add the minor gridlines.

The spacing of the minor gridlines helps remind you how the scale works, and you can also use them as a guide. The line immediately above 1000 is 2000, then the next one is 3000, etc., and they are spaced accordingly.

I love these types of data representation issues and when I make a display that is more intelligible than it might have been, it makes me really happy and proud.