# raw.moments: Compute Raw Moments Matrix In sem1: Structural Equation Models

## Description

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

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13``` ```raw.moments(object, ...) ## S3 method for class 'formula' raw.moments(formula, data, subset, na.action, contrasts = NULL, ...) ## Default S3 method: raw.moments(object, ...) 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 `raw.moments` 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` of `model.matrix.default`

.

 `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

`raw.moments` 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 [email protected]

`sem`

## Examples

 ```1 2 3 4 5 6``` ```data(Kmenta) raw.moments(cbind(1, Kmenta)) raw.moments(~ Q + P + D + F + A, data=Kmenta) Cov <- with(Kmenta, cov(cbind(Q, P, D, F, A))) cov2raw(Cov, colMeans(Kmenta), nrow(Kmenta)) ```

sem1 documentation built on May 31, 2017, 4:54 a.m.