We are back and happy to be home!
Next up on our mutual agenda is a presentation by the pair of us and our friend on the subject of longevity. Our friend read "The Longevity Project", a book by Howard Friedman and Leslie Martin that reports the results of an analysis of data collected in Louis Terman's gifted children work at Stanford University in the 1920's. Terman gathered much information about the children in his project and kept gathering it all his life. After his death, the information gathering continued. Much of it is less that highly scientific but it does cover about 1500 people and does so for nearly their entire lifespan.
Friedman and Martin report the results of the correlational data analysis. It is frequently the case with humans that there is no way to conduct a double blind experiment where some people are designated to take treatment A and some are designated not to get the treatment. So, lacking experimental data, correlational studies are often the best that can be achieved. In a correlation study, the co-occurrence of two or more variables is studied. Thus, if we find that heavier people are happier and lighter people are less so, we might conclude that weight has something to do with happiness.
Doctoral students are often quizzed on their understanding of the limitations of correlation. Both experimental and correlation research have limitations. One of the most severe is the question of how the particular subjects (people) got into the study. Were they all from the same city? Were they all caucasian? Were they volunteers? We may find that people from some other city or physical group or who don't volunteer are quite different from those we studied but we might find this out later, after errors and mistreatments.
The special shortcoming of correlation analysis is the problem of causation. If one group smoked and one group didn't, if the smoking group is especially happy, we might conclude that smoking produces happiness. In a correlation study, we take individuals and compare their level on two or more variables but we have no information on cause. If the heavier people are happier, does weight produce happiness? Does happiness produce weight? Maybe there is a well-known third factor, one that we don't even know about, that produces both weight and happiness.
The strongest relation the researchers found between longevity and other variables was with "conscientiousness" . Those in the study who were most conscientious over their whole lives tended to also be the people who lived the longest. So, vote, keep your grass cut and brush your teeth if you want to live a long time. (Maybe!)
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Bill
Main blog: Fear, Fun and Filoz
Main web site: Kirbyvariety
