equate (version 1.2-0)

descriptives: Descriptive Statistics for a Frequency Table

Description

The functions mean.freqtab, sd.freqtab, skew.freqtab, and kurt.freqtab return the mean, standard deviation, skewness, and kurtosis for a frequency table of class freqtab. descript returns all four of these values along with the number of observations. min.freqtab and max.freqtab return the minimum and maximum. cov.freqtab returns the variance of a univariate frequency table and the covariance of a bivariate.

Usage

## S3 method for class 'freqtab':
mean(x, ...)
sd.freqtab(x)
skew.freqtab(x)
kurt.freqtab(x)
descript(x)
## S3 method for class 'freqtab':
min(x, ..., na.rm = FALSE)
## S3 method for class 'freqtab':
max(x, ..., na.rm = FALSE)
cov.freqtab(x)

Arguments

x

two-column matrix of class freqtab, where column 1 specifies the score scale and column 2 the frequencies for each score point. If x is a three-column bivariate frequency table

...

further arguments passed to or from other methods.

na.rm

logical indicating whether missing values should be removed, currently ignored since frequency tables cannot contain missing values.

Value

• descript returns a vector which includes the mean, standard deviation, skewness, kurtosis, and number of observations. Otherwise a vector of length one is returned.

See Also

freqtab

Examples

xtab <- as.freqtab(ACTmath[, 1:2])
descript(xtab)
mean(xtab)

set.seed(2008)
y <- round(rnorm(100, 100, 10))
ytab <- freqtab(y, xscale = 70:130)
min(y); min(ytab)
max(y); max(ytab)
cov.freqtab(ytab); var(y)

ny <- freqtab(x = KBneat$y[, 1], xscale = 0:36,
	v = KBneat$y[, 2], vscale = 0:12)
cov.freqtab(ny); cov(KBneat$y[, 1], KBneat$y[, 2])