Demographic and Health Surveys Methodology - Measure DHS

CalculationInitial sample weights are produced by the DHS sampler using the sample selection probabilities of eachhousehold and the response rates for households and for individuals. The initial weights are thenstandardized by dividing each weight by the average of the initial weights (equal to the sum of the initialweight divided by the sum of the number of cases) so that the sum of the standardized weights equals thesum of the cases over the entire sample. The standardization is done separately for each weight.Handling of Missing Values—Not applicableApplicationSample weights are calculated to six decimals but are presented in the standard recode files without thedecimal point. They need to be divided by 1,000,000 before use to approximate the number of cases.In tabulation programs, sampling weights need to be applied through the use of special commands.Examples:Notes and Considerationsa) In SPSS using the WEIGHT command with the weight variable:COMPUTE rweight = V005/1000000WEIGHT by rweight.b) In ISSA using the weight parameterrweight = V005/1000000x = xtab(table1, rweight).1. The sum of the sample weights only equals the number of cases for the entire sample and not forsubgroups such as urban and rural areas.2. Where there are no differential probabilities, weights may not be calculated since weights basedjust on response rates usually make little difference in results.3. Use of sample weights is appropriate when representative levels of statistics are desired, such aspercentages, means, and medians.4. Use of sample weights is inappropriate for estimating relationships, such as regression andcorrelation coefficients.5. Use of sample weights biases estimates of confidence intervals in most statistical packages sincethe number of weighted cases is taken to produce the confidence interval instead of the truenumber of observations. For oversampled areas or groups, use of the sample weights willdrastically overestimate sampling variances and confidence intervals for those groups.Guide to DHS Statistics 14 September 2003