This is achieved by obtaining replicate one-day intakes. Thus, it can be demonstrated that the presence of variance affects the estimation of prevalence of inadequate intakes or of excessive intakes. Improvement of the food composition data base by increasing replications will improve the confidence of the prevalence estimate, but the cost-effectiveness for this purpose needs to be examined very carefully. Another application of computed nutrient intakes is in connection with epidemiologic studiesas in regression or correlation analyses of the relationship between observed intake and some biological outcome. It has been demonstrated by several authors that an error term in the estimation of usual intake can attenuate correlations and will bias regression slopes toward 0 if intake is used as the independent variable.
Table assumes that all foods make an equal contribution to nutrient intake.
The phenomenon is illustrated in table 9. 5.81 5.96 Calcium 1,540.2 103.7 6.74 1,135. 5,142.0 683.0 13.28 a For composition variability, see table 5 Table 7. It is not important which variable is I or 2.