Afghanistan Mortality Survey 2010 - Measure DHS

where h represents the stratum which varies from 1 to H,m hy hix hif his the total number of clusters selected in the h th stratum,is the sum of the weighted values of variable y in the i th cluster in the h th stratum,is the sum of the weighted number of cases in the i th cluster in the h th stratum, andis the sampling fraction of PSU in the h th stratum which is usually ignoredThe Jackknife repeated replication method derives estimates of complex rates from each ofseveral replications of the parent sample, and calculates standard errors for these estimates using simpleformulae. Each replication considers all but one cluster in the calculation of the estimates. Pseudoindependentreplications are thus created. In the AMS 2010, there were 717 non-empty clusters. Hence,717 replications were created. The variance of a rate r is calculated as follows:2SE () r var()r 1kk ( 1)ki1( r r)i2in whichri kr ( k 1)r(i)where rr (i)kis the estimate computed from the full sample of 717 clusters,is the estimate computed from the reduced sample of 716 clusters (i th cluster excluded),andis the total number of clusters.In addition to the standard error, the program computes also the design effect (DEFT) for eachestimate, which is defined as the ratio between the standard error using the given sample design and thestandard error that would result if a simple random sample had been used. A DEFT value of 1.0 indicatesthat the sample design is as efficient as a simple random sample, while a value greater than 1.0 indicatesthe increase in the sampling error due to the use of a more complex and less statistically efficient design,such as multistage and cluster selection. The program also computes the relative standard error and theconfidence limits for the estimates.Sampling errors for the AMS 2010 are calculated for selected variables considered to be ofprimary interest. The results are presented in this appendix are for the country as a whole, for urban andrural areas, for each of the three study domains, and for each of 8 geographical regions. For each variable,the type of statistic (mean, proportion, or rate) and the base population are given in Table B.1. Tables B.2to B.15 present the value of the statistic (R), its standard error (SE), the number of unweighted (N-UNWE) and weighted (N-WEIG) cases, the design effect (DEFT), the relative standard error (SE/R), andthe 95 percent confidence limits (R±2SE), for each variable. The DEFT is considered undefined when thestandard error considering simple random sample is zero (when the estimate is close to 0 or 1). In the caseof the total fertility rate, the number of unweighted cases is not relevant, as there is no known unweightedvalue for woman-years of exposure to child-bearing.The confidence interval (e.g., as calculated for children ever born to women age 40-49) can beinterpreted as follows: the overall average from the national sample is 6.900 and its standard error is0.053. Therefore, to obtain the 95 percent confidence limits, one adds and subtracts twice the standarderror to the sample estimate, i.e., 6.900±2×0.053. There is a high probability (95 percent) that the trueaverage number of children ever born to all women over age 40 is between 6.794 and 7.007.154 | Appendix B