This reduction in size of the study population resulted in a
power to detect the observed differences, and the observed variances,
between the vegetable group and the retinol-rich and lowretinol,
low-carotene groups of 0.99 and 0.79, respectively, and
between the fruit group and the retinol-rich and low-retinol, lowcarotene
groups of 0.78 and 0.89, respectively. To detect a significant
difference with a power of 0.90 between the fruit and the
vegetable groups, ³258 subjects should have been studied. In
general, the power to detect differences in changes of serum
carotene concentrations among relevant groups was higher than
for serum retinol concentrations. There were no significant differences
between treatment groups in any of the characteristics
shown in Table 2.