Thursday, October 27, 2005

Emily says these are sweet smelling flowers and a butterfly to liven up your day. Posted by Picasa

Wednesday, October 26, 2005

Sometimes professors just don't listen

I have had this idea to use quantile-quantile comparisons to analyze AFIS distribution data. AFIS is a machine that takes a cotton sample runs it through a wheel with little combs and separates the fibers. The individual fibers are blown into an airstream in a narrow tube. In the middle of the tube is an optical sensor that registers when a fiber passes, its length, and thickness. It can tell the difference between tangled and single fibers as well as trash. It then classifies the fibers into length, fineness, and maturity categories, while keeping count on trash and tangles, called neps. The distribution of fibers of different lengths makes a big difference on spinning quality. So people want to select for the best distribution of fibers, not just the best mean length or upper quartile length.

Quantiles divide the distribution into regular divisions like the median is the 50% quantile. The mean is not a quantile. It is not a rank. Anyway, the distribution, if continuous, can be divided into as many quantiles as one could want. A box plot is a representation of the 25% quantile, 50% quantile, and 75% quantile making the box. The whiskers are usually the 5% quantile and 95 or 97.5% quantile. The length values for the same quantiles for different distributions can be compared. If they are the same then the distributions are identical. If different the pattern of differences is how the distributions differ.

Anyway, to make a short story even longer and more boring, I went to a Statistics professor to talk about my idea. He thought it was great, but he never has actually got around to hearing how I want to do it. He has lectured me for two visits on the details of quantiles and distributions. Not that it hasn't been helpful, but he doesn't realize that I already know what he is trying to teach me.

I want to know if what he is calling a p-p plot, or a sample quantile-quantile graphical approach can be extended to more than one comparison kinda like covariance analysis. The y would be the quantiles of the check cultivar. The x's the quantiles of the experimental cultivar. The equation would be y = B1*[Year]*[X] + B2*[Replication]*[X] + B3*[Genotype]*[X] + [error variance], where [] notes matrix. The test would be to see if the slopes for genotype, replication, and years are equal, as well as the intercepts. If this is not right, then the other test I thought of would be to look at the deviations from x=y for each distribution. He did tell me about graphing the quantiles as y-x = x so that it is around 0 instead of a slope of 1, then the area under the curve can be calculated, deviations again. This number can be treated like a Wilcoxon type statistic. I just need to read up on Wilcoxon statistics I vaguely remember them in terms of nonparametric statistics.

I will put pictures up for the steps in the next few days.

Well if that isn't boring enough for you I don't know what is. I think with a few more posts like this I can cut my readership back to 0. I need to include a few references to swimsuits or hot chicks or cute girls or something in order to get someone to read the site. Statistics just isn't sexy enough.

Monday, October 24, 2005

My species, again. Stelly needs the picture. Posted by Picasa

Thursday, October 20, 2005

Harvest is DONE, uh, well, kinda . . .

Ok we are not really done. We have 7 rows left and I haven't finished measuring heights or counting nodes. Augh.

The weather has been beautiful since our rain last week. The temperature is down to 90 and the mornings are a brisk 70 degrees. Nothing like Texas Fall weather. Employers really should interview candidates in Fall or Spring. Summer is just too oppressive here.

My field has three hawks that circle around waiting for us to scare vermin out of the brush. The other day one was sitting on the row ahead of us. The cotton plants were bent over under the weight and there was a rattling of bolls and breaking of limbs when he decided to take off.

Yesterday the cranes were out in the recently plowed field next door. The humingbirds are gone though and I haven't seen a monarch butterfly for a week. The black irridescent ones still hang around the morning glory vines. The vultures have stayed near the river or the road.

This year I haven't seen any snakes, lizards or turtles. Last year we had a large turtle that I took in the truck back to the pond near the lab. When I found it the turtle hissed at me, but did not run away or try to bite me. I put it in a box and drove back to lab. Just as I turned into the parking lot he managed to lunge out of the box and land in my lap. He tried to bite me as I was trying to turn the corner, so I batted at him and knocked him onto the floor, where he decided to hole up under the seat of the truck. I managed to get him out without getting bit and release him near the pond. He didn't seem grateful though. Kinda bitter if you ask me for a refugie turtle. I guess he didn't realize that the field was going to be plowed under.

Tuesday, October 18, 2005

Aleah at the party with Sheetal.  Posted by Picasa

Wednesday, October 12, 2005

Cotton harvest

Rita did not even come close to detroying us. It veered to the east on the last day and destroyed Beaumont and Port Arthur. But, now it is raining and my cotton is half picked and still in the field.

The problem is that with every rain the bolls hang lower and lower and then the cotton falls out onto the ground. The seeds absorb the moisture in the wet lint and then germinate. The little cotyledons in the boll die as soon as the sun dries everything out. The seeds die and the husks of seed coats get pulled through the gin and into the lint that I have to send in for testing. The fiber also gets weaker and weaker with rain and sun as well as accumulating dirt and trash from the wind and rain. All and all, not so good.

But, what can I do? I can't change the weather. If anyone knows how, please let me know, although with my luck it would have side effects and cause tornados instead of raining. Or worse stay insanely hot. Can you believe that it was over a 100 degrees just over a week ago?

We have a new student here in the lab, Stella from Greece. She is very nice. She is just discovering how difficult it is working here where no one is checking up on you or helping you to design good experiments.

I haven't written about Sheng Mei yet either. In part because this is a shared computer that I use and my blog is often up. I will change the settings so that a login is required after screen saver so that I can write about her. she is a different sort of person. To get to know her very well, one simply has to go to catforum, a sad site dedicated to people devoted entirely to cats. She posts on it 10-15 times a day and tells all the mundane, but strange parts of her life.

All I am going to say is that she tastes the cat food before she will give it to her 5 cats. So they only eat cat food that tastes good?

Anyway. I should not gossip.

Who knows. Maybe cat food is good. I should ask my little brother. We dared him to eat it when we were kids and he did. Maybe he liked it.