In “A Comparative Study of Nursing Home Residents …”, Aigner et al. write (p. 20)
Acute visits were significantly higher for the nurse practiticoner/physician team at 3.0 visits per year (± 2.4) versus 1.2 visits per year (± 1.5) for the physician-only group (P <0.0001)
Furthermore, (p. 19)
The statistical analysis was performed using the chi-squared or Fisher exact test for comparisons of percent and Student t test for comparison of means
I always thought that if confidence intervals overlap by that much, differences can’t be significant. Am I wrong?
Aigner, M. J., Drew, S., & Phipps, J. (2004). A comparative study of nursing home resident outcomes between care provided by nurse practitioners/physicians versus physicians only. Journal of the American Medical Directors Association, 5(1), 16-23.