waldchisq {corncob}

Wald-type chi-squared test

Description

Wald-type chi-squared test

Usage

waldchisq(
  mod,
  mod_null = NULL,
  restrictions = NULL,
  restrictions.phi = NULL,
  contrasts_DA = NULL,
  contrasts_DV = NULL,
  robust = FALSE
)

Arguments

mod

an object of class bbdml

mod_null

Optional. An object of class bbdml, should be nested within mod. If not included, need to include restrictions or restrictions.phi.

restrictions

Optional. Defaults to NULL. Numeric vector indicating the parameters associated with the abundance to test, or character vector with name of variable to test. Note that 1 is the intercept associated with the abundance.

restrictions.phi

Optional. Defaults to NULL. Numeric vector indicating the parameters associated with the dispersion to test, or character vector with name of variable to test. Note that 1 is the intercept associated with the dispersion.

contrasts_DA

List. Optional. Constructs a contrast matrix. List elements should be characters specifying contrasts in the parameters within formula. Note that this is only available with "Wald" value for test.

contrasts_DV

List. Optional. Constructs a contrast matrix. List elements should be characters specifying contrasts in the parameters within phi.formula. Note that this is only available with "Wald" value for test.

robust

Should robust standard errors be used? If not, model-based standard arras are used. Logical, defaults to FALSE.

Value

Matrix with wald test statistics and p-values. Only performs univariate tests.

P-value from Wald test.

Examples

data(soil_phylum_small_otu1)
mod1 <- bbdml(formula = cbind(W, M - W) ~ DayAmdmt,
phi.formula = ~ DayAmdmt,
data = soil_phylum_small_otu1)

mod2 <- bbdml(formula = cbind(W, M - W) ~ 1,
phi.formula = ~ 1,
data = soil_phylum_small_otu1)

# Example using mod_null
waldchisq(mod = mod1, mod_null = mod2)
waldchisq(mod = mod1, mod_null = mod2, robust = TRUE)

# Example using restrictions and restrictions.phi
waldchisq(mod = mod1, restrictions = 2, restrictions.phi = 2)
waldchisq(mod = mod1, restrictions = "DayAmdmt", restrictions.phi = "DayAmdmt")
waldchisq(mod = mod1, restrictions = 2, restrictions.phi = "DayAmdmt")
waldchisq(mod = mod1, restrictions = 2, restrictions.phi = 2, robust = TRUE)