# regTermTest

##### Wald test for a term in a regression model

Provides Wald test and working Wald and working likelihood ratio (Rao-Scott) test of the
hypothesis that all coefficients associated with a particular
regression term are zero (or have some other specified
values). Particularly useful as a substitute for `anova`

when not fitting by maximum likelihood.

- Keywords
- regression

##### Usage

```
regTermTest(model, test.terms, null=NULL,df=NULL,
method=c("Wald","WorkingWald","LRT"), lrt.approximation="saddlepoint")
```

##### Arguments

- model
- test.terms
Character string or one-sided formula giving name of term or terms to test

- null
Null hypothesis values for parameters. Default is zeros

- df
Denominator degrees of freedom for an F test. If

`NULL`

these are estimated from the model. Use`Inf`

for a chi-squared test.- method
If

`"Wald"`

, the Wald-type test; if`"LRT"`

the Rao-Scott test based on the estimated log likelihood ratio; If`"WorkingWald"`

the Wald-type test using the variance matrix under simple random sampling- lrt.approximation
method for approximating the distribution of the LRT and Working Wald statistic; see

`pchisqsum`

.

##### Details

The Wald test uses a chisquared or F distribution. The two
working-model tests come from the (misspecified) working model where the
observations are independent and the weights are frequency weights. For
categorical data, this is just the model fitted to the estimated
population crosstabulation. The Rao-Scott LRT statistic is the likelihood
ratio statistic in this model. The working Wald test statistic is the Wald statistic
in this model. The working-model tests do not have a chi-squared
sampling distribution: we use a linear combination of chi-squared or F
distributions as in `pchisqsum`

. I believe the working Wald
test is what SUDAAN refers to as a
"Satterthwaite adjusted Wald test".

To match other software you will typically need to use `lrt.approximation="satterthwaite"`

##### Value

An object of class `regTermTest`

or `regTermTestLRT`

.

##### Note

The `"LRT"`

method will not work if the model had starting values supplied for the regression coefficients. Instead, fit the two models separately and use `anova(model1, model2, force=TRUE)`

##### References

Rao, JNK, Scott, AJ (1984) "On Chi-squared Tests For Multiway Contingency Tables with Proportions Estimated From Survey Data" Annals of Statistics 12:46-60.

Lumley T, Scott A (2012) "Partial likelihood ratio tests for the Cox model under complex sampling" Statistics in Medicine 17 JUL 2012. DOI: 10.1002/sim.5492

Lumley T, Scott A (2014) "Tests for Regression Models Fitted to Survey Data" Australian and New Zealand Journal of Statistics 56:1-14 DOI: 10.1111/anzs.12065

##### See Also

##### Examples

```
# NOT RUN {
data(esoph)
model1 <- glm(cbind(ncases, ncontrols) ~ agegp + tobgp *
alcgp, data = esoph, family = binomial())
anova(model1)
regTermTest(model1,"tobgp")
regTermTest(model1,"tobgp:alcgp")
regTermTest(model1, ~alcgp+tobgp:alcgp)
data(api)
dclus2<-svydesign(id=~dnum+snum, weights=~pw, data=apiclus2)
model2<-svyglm(I(sch.wide=="Yes")~ell+meals+mobility, design=dclus2, family=quasibinomial())
regTermTest(model2, ~ell)
regTermTest(model2, ~ell,df=NULL)
regTermTest(model2, ~ell, method="LRT", df=Inf)
regTermTest(model2, ~ell+meals, method="LRT", df=NULL)
regTermTest(model2, ~ell+meals, method="WorkingWald", df=NULL)
# }
```

*Documentation reproduced from package survey, version 3.37, License: GPL-2 | GPL-3*