The mean birthweight of sample of 25 babies is 3500 g with a standard deviation of 500 g. Thus an approximate 95% confidence interval for the mean birthweight is:

A. 3000 to 4000 g B. 3100 to 3900 g C. 3300 to 3700 g D. 3400 to 3600 g E. 3450 to 3550 g Farndon et al. (2013) report the results of a randomised controlled trial which investigated the effectiveness of salicylic acid plasters (Corn plasters) compared with usual scalpel debridement for treatment of foot corns. One of the secondary outcome measures was the size of the index corn (in mm) measured at 3, 6, 9 and 12 months post‐randomisation.

Table 5.5 shows the outcome data.

Table 5.5

Transcribed Image Text:

Corn plaster Scalpel Size of (n = (n = Mean 95% confidence index 101) 101) interval corn Mean SD Mean SD SD Difference Lower Upper P-value (mm) Baseline 3.9 (1.7) 3.8 (1.8) 3 1.7 (1.5) 2.7 (2.3) -1.0 -1.5 -0.5 months 6 1.7 (1.6) 2.4 (2.2) -0.7 -1.2 -0.2 months 9 1.7 (1.6) 2.2 (2.1) -0.5 -1.2 0.1 months 12 1.3 (1.6) 2.3 (2.2) -1.0 -1.7 -0.2 0.01 months