R: Compute Raw Moments Matrix

rawMoments {sem} | R Documentation

## Compute Raw Moments Matrix

### Description

Computes the “uncorrected” sum-of-squares-and-products matrix divided by the number of observations.

### Usage

    ## S3 method for class 'formula'
    rawMoments(formula, data, subset, na.action,
        contrasts=NULL, ...)

    ## Default S3 method:
    rawMoments(object, na.rm=FALSE, ...)

    cov2raw(cov, mean, N, sd)

    ## S3 method for class 'rawmoments'
    print(x, ...)

### Arguments

`object` | a one-sided model formula or an object coercible to a numeric matrix.
`formula` | a one-sided model formula specifying the model matrix for which raw moments are to be computed; note that a constant is included if it is not explicitly suppressed by putting `-1` in the formula.
`data` | an optional data frame containing the variables in the formula. By default the variables are taken from the environment from which `rawMoments` is called.
`subset` | an optional vector specifying a subset of observations to be used in computing moments.
`na.action` | a function that indicates what should happen when the data contain `NA`s. The default is set by the `na.action` option.
`contrasts` | an optional list. See the `contrasts.arg` argument of `model.matrix.default`

.

`na.rm` | if `TRUE`, any data rows with missing data will be removed.
`cov` | a covariance or correlation matrix.
`mean` | a vector of means.
`N` | the number of observations on which the covariances or correlations are based.
`sd` | an optional vector of standard deviations, to be given if `cov` is a correlation matrix.
`x` | an object of class `rawmoments` to print.
`...` | arguments passed down.

### Value

`rawMoments` and `cov2raw` return an object of class `rawmoments`, which is simply a matrix with an attribute `"N"` that contains the number of observations on which the moments are based.

### Author(s)

John Fox jfox@mcmaster.ca

### See Also

`sem`

### Examples

    # the following are all equivalent (with the exception of the name of the intercept):

    rawMoments(cbind(1, Kmenta))

    rawMoments(~ Q + P + D + F + A, data=Kmenta)

    Cov <- with(Kmenta, cov(cbind(Q, P, D, F, A)))
    cov2raw(Cov, colMeans(Kmenta), nrow(Kmenta))

[Package sem version 3.1-13 Index]