Standard deviation versus mean of the number of days of infection (NDI) for Reports B  and C  compared with those of five other studies. Filled points, representing the data reproduced in tables 1 and 2, appear twice, with circles around them (assuming that the values reported as SDs were in fact SDs), and without circles (assuming that the values reported as SDs were SEs). Also shown are linear functions fitted by least squares to the data from the bronchitis groups (top fitted line, slope = 1.59), to the circled filled points (bottom fitted line, slope = 0.13), and to the uncircled filled points (middle fitted line, slope = 0.56). See Appendix 2 for more details.
Sternberg and Roberts Nutrition Journal 2006 5:30 doi:10.1186/1475-2891-5-30