geeUOmega | R Documentation |

This function is normally not to be called directly, but one should usually use `mgee`

(see warning below).

This function takes output from the `gee`

function from the `gee`

package and creates a score matrix
(i.e., estimating equation) and information array (i.e., minus the derivative of the estimating equation).
Note the function creates the X matrix assuming the data set is the same as it was for the original call to gee, see Warning section.

geeUOmega(geeOutput)

`geeOutput` |
object of class gee, output from gee function |

A gee object with two extra elements to the list, u and omega (see `saws`

).

It is safer to use the `mgee`

function, which internally calls `gee`

then `geeUOmega`

. If you do not use `mgee`

,
and instead call `geeUOmega`

directly,
there could be a problem if the data set has been changed after the initial `gee`

call. This is
because the model matrix (i.e., the X matrix) is not saved as part of the gee object, we must recreate it from the gee call. So it is created assuming that the
data argument in gee means the same thing that it did when gee was called. So if you change the data set between the original gee call and using the geeUOmega function, there may be problems.

The function recalculates the fitted.values and the residuals to the gee object, since in gee (version 4.13-18 at least) the fited.values and residuals can be wrong if there is an offset or if y is a matrix (as in the binomial model).

M.P. Fay, with some lines copied from `gee`

function

`gee`

,`mgee`

## example from gee help data(warpbreaks) geeout<-gee(breaks~tension,id=wool,data=warpbreaks,corstr="exchangeable") guo<-geeUOmega(geeout) saws(guo)

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