R: Non-parametric, Asymptotic P-values for Multivariate Linear...

manta {manta}

R Documentation

Non-parametric, Asymptotic P-values for Multivariate Linear Models

Description

Fits a multivariate linear model and computes test statistics and asymptotic P-values for predictors in a non-parametric manner.

Usage

manta(
  formula,
  data,
  transform = "none",
  type = "II",
  contrasts = NULL,
  subset = NULL,
  fit = FALSE
)

Arguments

`formula`	object of class "`formula`" (or one that can be coerced to that class): a symbolic description of the model to be fitted.
`data`	an optional data frame, list or environment (or object coercible by `as.data.frame` to a data frame) containing the variables in the model. If not found in data, the variables are taken from `environment(formula)`, typically the environment from which `manta` is called.
`transform`	transformation of the response variables: "`none`", "`sqrt`" or "`log`". Default is "`none`".
`type`	type of sum of squares: "`I`", "`II`" or "`III`". Default is "`II`".
`contrasts`	an optional list. See `contrasts.arg` in `model.matrix.default`. Default is "`contr.sum`" for ordered factors and "`contr.poly`" for unordered factors. Note that this is different from the default setting in `options("contrasts")`.
`subset`	subset of predictors for which summary statistics will be reported. Note that this is different from the "`subset`" argument in `lm`.
`fit`	logical. If `TRUE` the multivariate fit on transformed and centered responses is returned.

Details

A Y matrix is obtained after transforming (optionally) and centering the original response variables. Then, the multivariate fit obtained by lm can be used to compute sums of squares (type-I, type-II or type-III), pseudo-F statistics and asymptotic P-values for the terms specified by the formula in a non-parametric manner. The designations "type-II" and "type-III" correspond exactly to those used in Anova. "type-I" refers to sequential sums of squares.

Value

manta returns an object of class "manta", a list containing:

`call`	the matched call.
`aov.tab`	ANOVA table with Df, Sum Sq, Mean Sq, F values, partial R-squared and P-values.
`type`	the type of sum of squares (`"I"`, `"II"` or `"III"`).
`precision`	the precision in P-value computation.
`transform`	the transformation applied to the response variables.
`na.omit`	incomplete cases removed (see `na.omit`).
`fit`	if `fit = TRUE` the multivariate fit done on the transformed and centered response variables is also returned.

Author(s)

Diego Garrido-Martín