Description Objects from the Class Slots Methods Author(s) References See Also Examples

The `LADObj`

class holds model specification and output from
the Least Absolute Deviation `lad`

and Hypothesis Test `hypothesis.test`

commands. The `summary.LADObj`

class
represents the summary of these objects.

Objects can be created by calls of the form `new("LADObj", ...)`

or, more commonly, via the
`lad`

or `hypothesis.test`

function call.

`inputData`

:A

`data.frame`

used for the analysis. The first column is the group (if supplied) and the second is the variable for which the analysis was performed.`NumObs`

:The total number of observations in the original data set.

`NumVars`

:The total number of variables in the original data set.

`theta`

:The quantile used if quantile regression is desired.

`NumPerm`

:The number of permutations used.

`Test`

:A logical indicator of whether a hypothesis test was performed.

`DoublePermutation`

:A logical indicator of whether a double permutation was used this should only be

`TRUE`

for`hypothesis.test`

.`T_o`

:The dispersion test statistic equal to (sum of absolute deviations for reduced model - sum of absolute deviations for full model) / sum of absolute deviations for full model.

`AsyRankScore`

:If the option

`rank.score`

is set equal to true in the hypothesis test then this value contains the asymptotic rank score statistic.`P_value`

:The probability of a smaller or equal delta under the null hypothesis.

`P_valueTN`

:The P-Value of Asymptotic rank score statistic.

`Betas`

:A vector of regression coefficients in the full model fit.

`RedBetas`

:A vector of regression coefficients in the reduced model fit (if applicable).

`SumAbsValRes`

:The sum of absolute values of the residuals in the full model.

`SumAbsValResRed`

:The sum of absolute values of the residuals in the reduced model (if applicable).

`WtSumAbsDevsFulMod`

:The weighted sum of the absolute deviations in the full model.

`WtSumAbsDevsRedMod`

:The weighted sum of the absolute deviations in the full model (if applicable).

`NumIter`

:The number of iterations for model convergence.

`ExitCode`

:A numeric code indicating whether a solution was successfully found:

ExitCode = 1: Successful

ExitCode = 2: Rounding Error

ExitCode = 0: Non-Unique

ExitCode = 7: Multiple Solutions

`PermVals`

:if

`save.test`

was set equal to`TRUE`

and a hypothesis test was performed then this is a vector of the permutation values of the test statistic.`HasIntercept`

:A logical vector indicating whether the full and reduced models include intercept terms.

`DoAllQuants`

:A logical indicator of whether all quantile regression estimates were calculated.

`DoRankScore`

:A logical indicator of whether a rank score test was performed.

`IsOLS`

:A logical indicator of whether ordinary least squares regression was performed.

`NumLaVars`

:A vector with the number of variables in the full and reduced models.

`ResRed`

:Residuals from the reduced model (if applicable).

`Resids`

:Residuals from the full model.

`Call`

:The original function call.

`response`

:The response vector used in the model fit.

`full.mod.names`

:The names of predictors used in the full model for hypothesis testing.

`QuantOut`

:If

`all.quants`

was true in the function code this is a matrix containing the quantile values. Using the function`QuantValues()`

will display these in a useful manner.

- coefficients
`signature(x = "LADObj")`

: Returns the coefficients from the model fit.- predict
`signature(x = "LADObj")`

: Reports the predicted values from the model fit.`signature(x = "LADObj")`

: Same as`summary`

.- pvalue
`signature(x = "LADObj")`

: Returns the p-value from the`LadObj`

assuming a hypothesis test was specified.- QuantValues
`signature(x = "LadObj")`

: Reports all quantile regression estimates if`all.quants`

was set to`TRUE`

.- ResampVals
`signature(x = "LADObj")`

: Returns the resample values if applicable.- residuals
`signature(x = "LADObj")`

: Returns the residuals from the full model fit.- show
`signature(object = "LADObj")`

: Same as`summary`

.- summary
`signature(object = "LADObj")`

: Prints a detailed summary of the LAD fit.

Marian Talbert

Cade, B.S. and J.D. Richards. 1996. Permutation tests for least absolute deviation regression. *Biometrics* **52**, 886–902.

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