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)
#> [1] 6.60754e-06
#> attr(,"df")
#> [1] 2
waldchisq(mod = mod1, mod_null = mod2, robust = TRUE)
#> [1] 0.0001905122
#> attr(,"df")
#> [1] 2

# Example using restrictions and restrictions.phi
waldchisq(mod = mod1, restrictions = 2, restrictions.phi = 2)
#> [1] 6.60754e-06
#> attr(,"df")
#> [1] 2
waldchisq(mod = mod1, restrictions = "DayAmdmt", restrictions.phi = "DayAmdmt")
#> [1] 6.60754e-06
#> attr(,"df")
#> [1] 2
waldchisq(mod = mod1, restrictions = 2, restrictions.phi = "DayAmdmt")
#> [1] 6.60754e-06
#> attr(,"df")
#> [1] 2
waldchisq(mod = mod1, restrictions = 2, restrictions.phi = 2, robust = TRUE)
#> [1] 0.0001905122
#> attr(,"df")
#> [1] 2