Table 1.

Power (in percentage) for 20 nmol/L equivalent dose at $u=2$ for a range of sample sizes and baseline population 25OHD concentrations.

n (per arm)	15 nmol/L	35 nmol/L	50 nmol/L	60 nmol/L	75 nmol/L
100	19.1	36.6	28.9	16.8	8.1
200	25.6	54.2	42.1	23.3	8.9
300	35.2	70.5	54.6	28.9	10.0
400	44.2	81.8	67.3	37.8	11.6
500	49.8	88.2	74.8	41.3	12.1
600	56.1	93.3	81.8	49.1	13.3
700	64.0	96.6	87.6	54.8	16.0
800	68.2	97.3	90.5	60.4	16.7
900	71.4	98.7	92.8	63.8	16.5
1000	76.5	99.1	95.3	67.5	18.5
1100	79.2	99.5	96.8	72.8	19.4
1200	83.3	99.8	97.7	75.1	19.2
1300	85.5	99.9	98.6	77.5	21.7
1400	88.0	99.9	98.8	81.0	21.2
1500	90.8	100.0	99.1	84.6	21.8

Designs having $\ge 80\%$ power are in bold font.