Happenings – 2010 Dec 18

This will be a very short post.

Since last Saturday morning I’ve managed to do some abstract algebra – I’ve started chapter 2 (!) of Dummit & Foote’s “Abstract Algebra”. I also started playing with Lynch’s “Dynamical Systems with Applications using Mathematica”.

And I have done absolutely no work on the next blog post, but since it is scheduled for January 10, there is no hurry.

Have a Merry Christmas.

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Happenings – 2010 Dec 12

It’s been a busy week… for things other than mathematics. And I never did do any mathematics or a blog post yesterday.

I did, however, do a little work on color theory last weekend and this weekend. To be specific, I have been taking photographs around my house… of things that are partly in shade. On the first day, the sky was clear and the contrast between shade and light was quite extreme. But yesterday was partly cloudy and the contrast was much less: I may not be able to get full shadow and partial shadow on the same day, but I can get both. Once I realized that, I just had to go out and take pictures.

Now, all I have for displaying the digital images is my computer monitor… and we know that that is nonlinear. Nevertheless, I can now investigate “shadow series”: the objective differences between a given color seen in shadow and seen in light.
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Regression 1: Example 4, Baseball Attendance


Let us work another example from Ramanathan. In fact, this is one of his exercises… for which he provides a fairly detailed list of questions. Perhaps I should emphasize that although I am using his dataset, this does not answer his questions. In other words, I’m about to single out the best regressions, but I’m not going beyond that.

On the other hand, his problem statement does suggest a backward selection, so I’m “doing the homework” to that extent.

Here is a description of the data based on the 4th edition file, which included descriptive information; the 5th edition data contains the variable names but nothing else (that I saw). I am, in fact, using the 5th edition data, despite the 4th edition description.

I showed you earlier where to get his data.

Data on the factors affecting baseball attendance — compiled by Scott Daniel. Read the rest of this entry »

Happenings – 2010 Dec 4

What’s up?

First of all, I have two comments about the blog. One, the CIE chromaticity chart has passed the first axis and angle of rotation post as the number one post on the blog, all time. Second, the post about the minimum number of triangles in a triangulation has moved slightly ahead of the tint-tone-shade color post. I suspect, however, that those two posts will keep changing places… we’ll see.

Just for the fun of it, here is a screenshot of the 14 posts which have more than 1000 hits all-time, as of a few minutes ago.

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