Contrast fixed effects — contrast.mm

Note: this is not emmeans::contrast. contrast() is mixeff's fixed-effect contrast front door. R validates the contrast matrix shape, then asks Rust to evaluate estimability, method prerequisites, standard errors, degrees of freedom, statistics, p-values, reliability, and unavailable reasons.

Usage

# S3 method for class 'mm_glmm'
contrast(fit, L, rhs = 0, method = c("asymptotic", "wald"), ...)

contrast(
  fit,
  L,
  rhs = 0,
  method = c("auto", "satterthwaite", "kenward_roger", "bootstrap", "asymptotic",
    "boundary_lrt", "none"),
  bootstrap = NULL,
  ...
)

# S3 method for class 'mm_lmm'
contrast(
  fit,
  L,
  rhs = 0,
  method = c("auto", "satterthwaite", "kenward_roger", "bootstrap", "asymptotic",
    "boundary_lrt", "none"),
  bootstrap = NULL,
  ...
)

Arguments

fit: A fitted mm_lmm.
L: A numeric contrast vector or matrix with one column per fixed effect.
rhs: Numeric right-hand side, recycled to the number of contrasts.
method: Requested inference method.
...: Reserved for future methods.
bootstrap: Optional bootstrap_control() object for method = "bootstrap".

Value

An mm_contrast object with a data-frame table. The estimate column is the tested difference, L beta_hat - rhs.

Details

For mm_glmm fits, contrasts use an asymptotic Wald z-test built from the stored fixed-effect covariance (the GLMM contract does not provide finite-sample df), so method accepts only "asymptotic" (alias "wald").