PROC SURVEYMEANS: Ratio :: SAS/STAT(R) 9.2 User's Guide, Second Edition

The SURVEYMEANS Procedure

Ratio

When you use a RATIO statement, the procedure produces statistics requested by the statistic-keywords in the PROC SURVEYMEANS statement.

Suppose that you want to calculate the ratio of variable $\text{[math]}$ over variable $\text{[math]}$ . Let $\text{[math]}$ be the value of variable $\text{[math]}$ for the $\text{[math]}$ th member in cluster $\text{[math]}$ in the $\text{[math]}$ th stratum.

The ratio of $\text{[math]}$ over $\text{[math]}$ is

$\text{[math]}$

PROC SURVEYMEANS uses the Taylor series method to estimate the variance of the ratio $\text{[math]}$ as

$\text{[math]}$

where if $\text{[math]}$ ,

$\text{[math]}$	$\text{[math]}$	$\text{[math]}$
$\text{[math]}$	$\text{[math]}$	$\text{[math]}$
$\text{[math]}$	$\text{[math]}$	$\text{[math]}$

and if $\text{[math]}$ ,

$\text{[math]}$

The standard error of the ratio is the square root of the estimated variance:

$\text{[math]}$

When the denominator for a ratio is zero, then the value of the ratio is displayed as '–Infty', 'Infty', or a missing value, depending on whether the numerator is negative, positive, or zero, respectively; and the corresponding internal value is the special missing value '.M', the special missing value '.I', or the usual missing value, respectively.

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