Monday, February 23, 2015

Did my LDL particles get larger?

Low Density Lipoprotein (LDL)l, commonly called the "bad cholesterol",  is linked with high risk of heart disease. But just the total mass of LDL doesn't tell the whole story.

Wednesday, February 18, 2015

Walkabout wednesday

Why don't epidemiologists use model simplification?

Monday, February 16, 2015

Sometimes we should not avoid Type I errors

In any introductory statistics course you will learn how to control the probability of making a Type I error. This is the error of concluding that the alternative hypothesis is true, when in fact it is not. But sometimes that kind of error is much, much better than the opposite.

Friday, February 13, 2015

Gluten, again.

A colleague brought this post on the fivethirtyeight blog on the gluten free fad to my attention. They make a couple of good points about Non-celiac gluten sensitivity (NCGS), focusing mainly on a couple of studies done by a group in Australia. I wrote about these 2 studies in my post on why I went gluten free. The 2011 study found that NCGS was real, and found that perhaps 10% of people suffered from it. However, science, you know, so they modified their design and repeated the study, and their 2013 paper found that the effect was not due to gluten but rather to Fermentable Oligo- Di- Monosaccarides and Polyols, or FODMAPs for short. FODMAPs are found in lots of plant foods including foods containing gluten.

FWIW, the 2013 study was funded by the Australian Wheat Board*, so keep the source in mind when looking at the conclusions!

The main point that Emily Oster is trying to make is that many people are jumping on the Gluten Free bandwagon unnecessarily, and that is creating a market opportunity for food manufacturers. Yep, I can see that; 30% of the population buying gluten free products is way higher than any estimate of NCGS prevalence. It's worth noting that the only estimates of NCGS prevalence are from surveys asking people if they avoid gluten in their diets; answer yes, and boom, you're considered to be a NCGS sufferer. What makes that interesting is that those prevalence estimates are on the order of 1%! So, only 1% of people say they are avoiding gluten, but 30% of the population are buying gluten free products. Hm. Well, no one insists that your personal choices have to be consistent or make sense.

For my part, I avoid gluten by not eating refined carbohydrates to control my blood sugar, so even if there's no effect of gluten on my physiology, I'm not going to start eating bread again. Beer. Well, the odd beer might creep in there.

Besides bloating and flatulence, there's the disturbing possibility that gluten rots your brain. Even the possibility of that being true is enough to make limiting gluten attractive to me. Maybe time to revisit the distinction between Type I and Type II errors in decision making, as opposed to statistical hypothesis testing.

*I mentioned the funding source thing before too.

Wednesday, February 11, 2015

Walkabout Wednesday: angiogenisis is interesting, and more politics in the environment (surprise ...)

Angiogenisis is the formation of blood vessels, are your professors lazy, and politics taking over sage grouse management in Montana.

Tuesday, February 10, 2015