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Appendix D: Assessing the Performance of the EAR Cut-Point Method for Estimating Prevalence
Pages 211-231

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From page 211... ... As stated in Chapter 4, the EAR cut-point method produces reliable estimates of the proportion of inclivicluals in a group whose usual intakes do not meet their requirements, as long as the following assumptions hold � intakes and requirements of the nutrient are inclepenclent; � the distribution of requirements in the group is symmetrical about the EAR; and � the variance of the distribution of requirements is smaller than the variance of the distribution of usual intakes. A reliable estimate of the distribution of usual intakes in the group 211 Read the entire page →
From page 212... ... was larger than the standard deviation of usual intakes (8Di) Read the entire page →
From page 213... ... In Figures D-1 through D-9, the solid lines and dots represent the true prevalence at each value of the correlation between intakes and requirements. The dashed lines and squares represent the average estimates of prevalence (over the 200 replicates) Read the entire page →
From page 214... ... cut-point method for 10 values of the correlation. For all correlations, mean intake = 90, standard deviation (SD) Read the entire page →
From page 215... ... For all correlations, mean intake = 90, standard deviation (SD) of intake = 30, EAR = 55, and SD of requirement = 15 units. Read the entire page →
From page 216... ... For all correlations, mean intake = 90, standard deviation (SD) of intake = 30, EAR = 55, and SD of requirement = 30 units. Read the entire page →
From page 217... ... _ 24 20 16~5 cat . _ o c' cat g 12 84O~ -- -- -- -- - -- -- -- -- ___ � � True prevalence \ ~ - ~ EAR cut-point estimated prevalence \~ 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Correlation coefficient FIGURE D-5 The effect of correlation between usual intake and requirement on the prevalence of inadequate intakes estimated using the Estimated Average Requirement (EAR) Read the entire page →
From page 218... ... _ Cot .O Cot ~ 12Cot . _ o C' DIETARY REFERENCE INTAKES 28 24 20 16 84o -- -~ ~ -- -~ -- -~- ~ -- ~ -- -~ ~ -- -~ -- -~ \ � � True prevalence a -- EAR cut-point estimated prevalence \ 1 l l l l l l l l l l 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Correlation coefficient FIGURE D-6 The effect of correlation between usual intake and requirement on the prevalence of inadequate intakes estimated using the Estimated Average Requirement (EAR) Read the entire page →
From page 219... ... cut-point method for lo values of the correlation. For all correlations, mean intake = 90, standard deviation (SD) Read the entire page →
From page 220... ... cut-point method for 10 values of the correlation. For all correlations, mean intake = 90, standard deviation (SD) Read the entire page →
From page 221... ... For all correlations, mean intake = 90, standard deviation (SD) of intake = 30, EAR = 90, and SD of requirement = 30 units. Read the entire page →
From page 222... ... For all correlations, mean intake = 90, standard deviation (SD) of intake = 30, and EAR = 70. Read the entire page →
From page 223... ... For all correlations, mean intake = 90, standard deviation (SD) of intake = 30, and EAR = 90. Read the entire page →
From page 224... ... VARIANCE OF REQUIREMENTS IS LARGE RELATIVE TO VARIANCE OF INTAKES To test the effect of violating the assumption that variance of requirements must be substantially smaller than variance of intakes for good performance of the Estimated Average Requirement (EAR) cut-point method, various scenarios were consiclereci. Read the entire page →
From page 225... ... _ Id Cal 12. _ a c' Is 24 20 16 84O� � True prevalence -- ~ EAR cut-point estimated prevalence 0 5 10 15 20 25 SD of requirement 30 35 40 FIGURE D-14 Effect of the standard deviation of requirement (SDr) Read the entire page →
From page 226... ... - o o� ~> 45.- 4035 30 20~5 25 15 10 O� � True prevalence -- ~ EAR cut-point estimated prevalence 0 5 10 15 20 25 30 35 40 SD of requirement FIGURE D-16 Effect of the standard deviation of requirement (SDrj on the estimated prevalence of inadequate intakes using the Estimated Average Requirement (EAR) cut-point method for 10 values of the SDr. Read the entire page →
From page 227... ... I ~ ~ Q M ~ 20.' 0' 10, 0 3, o tic ~ ~1~ ~ -10~ _` ~ ~ -20._ (a Q 30 - � � EAR = 55 - -- -+ EAR = 70 ~ - ~ EAR = 90 r ~ -- I -- -- ~ -- -- ~ -- -- -~ -- -- -~ -- -- ~ -- -- ~ 0 5 10 15 20 25 SD of requirement 30 35 40 FIGURE D-17 Effect of the standard deviation of requirement (SDr) on bias of the estimated prevalence of inadequate intakes using the Estimated Average Requirement (EAR) Read the entire page →
From page 228... ... A situation in which the variance of intake may become small relative to the variance of requirements is for instituit ~ ~ Q an .= Q s 1 o tr ~ i ~ -10 ~ -20 ._ to m a' Q 30 20 10 O� � EAR = 55 + -- -+ EAR = 70 - ~ EAR = 90 Gus__ -- ~ -- -- {} -- -- {} -- -- ~ -- -- -o -- -- -~ -- -- ~ no= ~ _ 0 5 10 15 20 25 SD of requirement 30 35 40 FIGURE D-18 Effect of the standard deviation of requirement (SDr) on bias of the estimated prevalence of inadequate intakes using the Estimated Average Requirement (EAR) Read the entire page →
From page 229... ... Recall that for a symmetrical distribution, the value of the skewness coefficient is equal to zero; thus, increasing skewness reflects increasing departures from symmetry. Intakes were simulated inclepenclently as normal random variables with a mean intake of 12 ma, and stanciarci deviation of 3 mg resulting in a CV of intake of 25 percent. Read the entire page →
From page 230... ... Bias ( % ) 8.4 0.7 0.62 12 11 1 8.6 1.4 1.32 15 1 1 4 9.0 2.5 2.51 20 1 1 9 9.5 3.9 3.15 24 11 13 10.4 6.9 5.73 28 12 16 NOTE: The distribution of usual intakes is fixed to be normal with a mean of 12 mg and a standard deviation of 3 ma. Read the entire page →
From page 231... ... cut-point method for five values of skewness. For all levels of skewness, mean intake = 12 ma, standard deviation (SD) Read the entire page →

From page 211...

... As stated in Chapter 4, the EAR cut-point method produces reliable estimates of the proportion of inclivicluals in a group whose usual intakes do not meet their requirements, as long as the following assumptions hold � intakes and requirements of the nutrient are inclepenclent; � the distribution of requirements in the group is symmetrical about the EAR; and � the variance of the distribution of requirements is smaller than the variance of the distribution of usual intakes. A reliable estimate of the distribution of usual intakes in the group 211

Appendix D: Assessing the Performance of the EAR Cut-Point Method for Estimating Prevalence Pages 211-231

Appendix D: Assessing the Performance of the EAR Cut-Point Method for Estimating Prevalence
Pages 211-231