| sigmaMenu | R Documentation | 
Within the "Statistics" -> "Variances" menu, a new entry is provided for calculate
confidence intervals and make contrasts on variance in a normal
population. This option uses the function sigma.test of the
package TeachingDemos. For more information see sigma.test.
Here is an example of "Single-Sample Variance Test..." menu entry.
Load data "sweetpotato" selecting from Rcmdr menu: "Data" -> "Data in packages" -> "Read data set from an attached package..." then double-click on "randtests", click on "sweetpotato" and on "OK". Rcmdr reply with the following command in source pane (R Script)
data(sweetpotato, package="randtests")
sweetpotato <- as.data.frame(sweetpotato)
To build a confidence interval for sigma on variable "yield", select from Rcmdr menu: "Statistics" -> "Variances" -> "Single-sample Variance Test..." select "yield" and "OK". Rcmdr reply with the following command in source pane (R Script)
with(sweetpotato, sigma.test(yield[!is.na(yield)], alternative='two.sided', sigmasq=1.0, conf.level=0.95))
Manuel Munoz-Marquez <manuel.munoz@uca.es>
For more information see Rcmdr-package. 
Para ayuda en español, véase
Test de varianza (es). (For Spanish help see Test de varianza (es).) 
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