In the study of Langewitz et al. (2002) of the length of time for which patients spoke when explaining their problem to a doctor, The authors reported the following:
"Of the 330 patients who provided sociodemographic data, . . . mean age was 42.9 years (SD 18.2 (95% confidence interval 17 to 84) years)."
(Note that mean ± 1.96 standard deviations = 7.2 to 78.6 years, mean ± 1.96 standard errors = 40.9 to 44.9 years.)
What is wrong with this confidence interval?
Langewitz W, Denz M, Keller A, Kiss A, Rüttimann A, Wössmer B. (2002) Spontaneous talking time at start of consultation in outpatient clinic: cohort study. British Medical Journal 325, 682-683.
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Last updated: 19 January, 2009.