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KAIS 2007 1 - Kenya National AIDS & STI Control Programme ...

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This report presents the results of univariate and bivariate analyses using the <strong>2007</strong> <strong>KAIS</strong>data. Analyses are not adjusted for any confounding factors; multivariate analyses havebeen reserved for other dissemination materials, such as scientific manuscripts. Byconvention, we present weighted proportions (except where noted) and unweightedfrequencies. In addition to weights, appropriate survey design variables were included inthe analyses to obtain standard errors and chi‐square p‐values. Weighted proportions basedon a denominator of less than 25 participants were suppressed in the chapters andappendices given the instability of the estimate, although the corresponding unweightednumber of cases and unweighted total (unweighted n/N) was still presented in Appendix B.Most analyses were stratified by sex given the importance of this variable in understandingthe distribution of HIV, HSV‐2, and syphilis. With the exception of Chapter 3 (Trends in HIVPrevalence), statistical significance was assessed based on chi‐square p‐values produced instandard statistical software packages. In Chapter 3, we assumed the estimates from the2003 KDHS and the <strong>2007</strong> <strong>KAIS</strong> were independent and used the z‐test to compare twoweighted estimates and determine if differences were statistically significant. The z‐statisticwas constructed as the difference in the point estimates between 2003 and <strong>2007</strong> divided bythe standard error of the difference:Z =( )p<strong>2007</strong>− p2003( +<strong>2007</strong> varvar 2003)where var<strong>2007</strong> and var2003 are the variances for the two estimates.We used the z‐statistic to calculate a p‐value for differences between estimates in 2003 and<strong>2007</strong>. Throughout the report, the term significant indicates a p‐value less than 0.05.Marginally significant indicates a p‐value between 0.05 and 0.10; and not significantindicates a p‐value greater than 0.10. Terms such as “apparent” or “appears to be” refer tothe general shape of the graph or a possible pattern of data that has not been formallyevaluated with a statistical test; such testing was beyond the scope of this report.The program used for the analysis of the <strong>2007</strong> <strong>KAIS</strong> data was SAS version V9.13. Thisprogram accounts for the clustered, stratified design of the <strong>KAIS</strong> survey sample and canproduce reliable standard errors and confidence intervals.<strong>KAIS</strong> <strong>2007</strong> 302

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