px function

Percentile Ranks and Cumulative Frequencies

These functions compute percentile ranks and cumulative frequency distributions for frequency tables.

px(x, ...)

## Default S3 method:
px(x, y, ys, ...)

## S3 method for class 'freqtab'
px(x, margin = 1, y, ymargin = 1, ...)

fx(x, ...)

## Default S3 method:
fx(x, ...)

## S3 method for class 'freqtab'
fx(x, margin = 1, ...)

Arguments

• x: either a vector of counts, or an object of class ‘freqtab’ from which counts will be taken.
• ...: further arguments passed to or from other methods.
• y: an object of class ‘freqtab’ when x is as well, otherwise, a vector or data.frame of counts. See below for details.
• ys: vector specifying the y score scale, when it is not contained in the first column of y. If y can be converted to a data.frame, it is assumed to be univariate with the first column containing the score scale and the second containing the counts.
• margin, ymargin: integers specifying the margins for which frequencies or percentile ranks will be returned. margin applies to x and ymargin to y.

Returns

A vector is returned containing either percentile ranks or cumulative frequencies with length equal to length(x).

Details

These functions compute percentile ranks and cumulative frequencies for a univariate distribution, and percentile ranks from one univariate distribution (x) corresponding to score values in another (y).

Examples

x <- as.freqtab(ACTmath[, 1:2], drop = TRUE)
y <- as.freqtab(ACTmath[, c(1, 3)], drop = TRUE)

# Percentile ranks for the x scale
round(px(x), 3)

# Percentile ranks in y for x each score
round(px(x, y = y), 3)

# Cumulative frequency distribution for x
round(fx(x), 3)

See Also

freqtab

Author(s)

Anthony Albano tony.d.albano@gmail.com