Category: Statistics Articles

Decreasing Body Temperatures

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Researchers at Stanford University used data from the Union Army Veterans of the Civil War (1860-1940), the National Health and Nutrition Examination Survey (1971-1975), and the Stanford Translational Research Integrated Database Environment (2007-2017) to determine that the mean body temperature in men and women has decreased by 0.03 degrees Celsius per birth decade.  The reduction in body temperature is a proxy for metabolic rate and this may help to explain the changes in the health of humans and the increase in life expectancy. In 1851, Carl Reinhold August Wunderlich measured the body temperature of 25,000 humans and found that normal body temperature was 98.6 degrees Fahrenheit (or 37 degrees Celsius).  […]

Frames in Polling

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Random-digit-dialing (RDD) is a popular method for selecting people to be in polls.  So, the population from which a sample is drawn is anyone with a telephone (because RDD dials both listed and unlisted numbers).  A problem with RDD is that of bias as a result of nonresponse.A study by Pew Research compared polling results using random-digit-dialing to the use of registered voter files.  In this study, it was found that in 56 of 65 survey questions, the two polling methods resulted in estimates that were statistically insignificant.Have your students read the article and discuss issues such as frames, nonresponse bias, under-representation, and the overall challenges in finding a sample […]

Beware the Lurking Variable

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I just completed the discussion on correlation and regression with my Introductory Statistics students. One of the recommendations within the new GAISE outline is to introduce students to multivariate analysis.  A classic application of this practice is the SAT score versus teacher salary data. This data may be found by joining a group I created in StatCrunch titled “SullyStats”. To join the group, go to www.statcrunch.com (if you don’t have a StatCrunch account, ask you Pearson representative for an account).  Under Explore, select Groups. Type SullyStats into the search box and join the group.  The data set is titled “SAT versus Teacher Salaries“ Use the data to illustrate the danger […]