Wednesday, February 02, 2011

Home again today

They cancelled classes for today again. Which was probably wise because the streets are completely ice covered.

(I hope by some miracle it goes away today, or gets crunched up, or some other municipality takes pity on us and sends us some MgCl2, because I think I will be bored with being home after today).

Yesterday, when I was not goofing around online, I read a bunch of research-related articles. Which reminds me, a great quotation from one, on the timing and severity of wildfires in Oklahoma and if they could be predicted from weather patterns:

"One interesting exception [to the usual pattern of early spring fires] occurred in the month of July, which had a relatively high number of wildfires but low area burned. This was due to the Fourth of July holiday.*"

Or, as I think I'd refer to it as, the "Oh s____, RUN!" factor....Or the "light fuse and get away" factor. (from the instruction on nearly every available-to-the-public explodey type firework. And yeah, my family used to set them off. Or at least, the men did. I tend to think that that form of pyromania must be a Y-chromosome linked gene.)

(*Reid, Fuhlendorf, and Weir, 2010 - Rangeland Ecology and Management)

Incidentally - Shannon-Weaver index. I guess the source Charles looked at did a good job of obfuscating it, because it's really not THAT hard to calculate. The version of it I do (there are a couple ways of getting to the answer) is based on proportions and logarithms of those proportions. Not that hard. Or at least, not that hard once you've used it a few times, perhaps. (I've been using it since, I don't know, 1989? Basic Intro Ecology at Michigan?)

Unless I really am unusually mathematically gifted, which some of my students try to make me believe...so they can explain why they "can't" do the graphing or calculations I ask them to do.

(There's another version that's more complex to calculate, based on frequencies and numbers and the equation looks scarier, but it gives the same result. Also, some people use a base-10 logarithm and some use a natural log (base e). I usually use base-10 because most of the publications I've read that use it seem to use that; it may be a difference among different subdisciplines of ecology)

***

After I get done on here, I'm taking today as a Fun Day. Haven't yet decided whether to work on the various socks-on-the-needles (I finished the first Paton's ombre yarn sock last night and started the second, got the ribbing of it mostly done during Dirty Jobs), or to do the neckline of Thermal (I am still waiting for the spots on my chin to heal before I take another photo of myself, however. I claim not to be vain but maybe I am, a little) or whether to brave the chill of my sewing room and work on the current quilt (Which actually kind of appeals to me, and maybe I could safely set up the space heater in there. I like working on quilt tops when I have a big block of free time because it's easier to get knitting done in the little odds and ends of time I have at the end of the day).

2 comments:

Jennifer said...

I have found that my students are confounded by the summation symbol. They just haven't really run across it before and don't know what to do with it.

CGHill said...

I can believe that; a really large sigma is intimidating all by itself.

The version I looked at used natural logs, which is no big deal in and of itself - base 10 or base e, it's still the same rules - but I got bogged down in some of the derivation. The index itself is fairly easy to calculate; demonstrating its validity is a bit trickier.