The SURVEYMEANS Procedure

Confidence Limits for the Total

If you specify the keyword CLSUM, the procedure computes confidence limits for the total. The confidence coefficient is determined by the value of the ALPHA= option, which by default equals 0.05 and produces 95% confidence limits. The confidence limits are computed as

$\widehat{Y} \pm \mbox{Std}(\widehat{Y})~ \cdot ~ t_{\mi {df},\, \, \alpha /2}$

where $\widehat{Y}$ is the estimate of the total, $\mbox{Std}(\widehat{Y})$ is the estimated standard deviation, and $t_{\mi {df},\, \, \alpha /2}$ is the $100(1-\alpha /2)$ percentile of the t distribution with df calculated as described in the section t Test for the Mean.

If you specify the keyword UCLSUM, the procedure computes the one-sided upper $100(1-\alpha )$ % confidence limit for the sum:

$\widehat{Y} + \mbox{Std}(\widehat{Y})~ \cdot ~ t_{\mi {df},\, \, \alpha }$

If you specify the keyword LCLSUM, the procedure computes the one-sided lower $100(1-\alpha )$ % confidence limit for the sum:

$\widehat{Y} - \mbox{Std}(\widehat{Y})~ \cdot ~ t_{\mi {df},\, \, \alpha }$