Wednesday, April 05, 2006

Bad science watch

Minnesota Public Radio ran a story this morning detailing the findings of a Mayo Clinic study on the prevalence of cognitive imparments among a sampling of older people in Olmstead county, Minnesota (scroll down):
Study links lack of education to Alzheimers
The preliminary findings of a Mayo Clinic study sshow seniors with lower levels of education have a greater chance of getting Alzheimer's Disease.

The study was a random sample of 70 to 90 year olds in Olmsted County. Those with eighth grade education levels were three times as likely to have mild cognitive impairment, that is the pre-cursor to Alzheimer's.

Dr. Ron Petersen conducted the study. He said he can't say people with more education are less likely to get the disease.

"But that would be consistent with what we're seeing in the field of Alzheimer's Disease research in general. Those individuals who remain cognitively active earlier in life have a lower risk of developing Alzheimer's in the future," he said.

Overall about 15 percent of the 4,000 people observed had mild cognitive impairment.

Now, maybe I'm just cognitively challenged in my senescence, but I would think that even a high school junior varsity debate team member can detect the flawed logic in Dr Petersen's conclusion. Coincidence does not denote causality. Could it be that both the lack of primary school success and the later onset of cognitive impairment result from some inherent underlying deficiency in cognitive capacity on the part of the subjects? Hmmmm.....


Blogger Harry Eagar said...

Well, I think he meant attendance through 8th grade,not high or low performance there.

The logical fallacy he is making is a different one, I think, which is that level of formal education attained equates to mental acuity.

The people he assessed were in the 8th grade, and might have been in high school, in Minnesota before 1945. Attendance in high school prewar in Minnesota depended almost entirely upon whether you lived in town or not. It had nothing to do with mental ability.

Near universal high school education did not start in the upper Midwest until all-weather roads were built in country districts. And that didn't happen until after 1945.

April 05, 2006 11:40 AM  
Blogger Duck said...

That's a good point Harry, but I think that it is safe to say, even at that time, that the cognitively challenged would be overrepresented in the 8th grade or less group. There are many factors to consider, and you mentioned one of them. You really can't understand the causal factors until you have identified all of the correlative factors and then conducted extensive studies on each set of factors individually and in different combinations to see which of them have the strongest correlation.

April 05, 2006 1:50 PM  
Blogger Harry Eagar said...

True enough.

For lack of easily found real data, the social scientists use proxies, and they are typically good only to a first approximation, if that.

When I was trying to learn economic history, I was amused to read how price series were constructed. There was much by-guess-and-by-god in them, but once published they became jewel-like in their lambent usefulness, and now, in my old age, I see them treated as if they really mean something.

This can be so even for events that were recent and sophisticated. For example, I am now reading a history of the shipping container (very interesting, too), and was surprised to learn that 21st century economists cannot figure out whether ocean shipping costs were rising or falling in the 1950s.

April 05, 2006 10:12 PM  

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