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Specify member-level attributes for mm() blocks

Source: R/helpers.R
vars.Rd

Helper function used within mm to specify the member-level attributes (the effect covariates \(x_{kt}\)) that the block's aggregation function fn reads. Supports both free variables (with coefficients estimated by the main model) and fixed variables (coefficients held constant via fix).

Usage

vars(...)

Arguments

...

Unquoted variable names, combined with + (formula-style) or as separate arguments. Supports:

  • Simple variables: vars(x + y) or vars(x, y)

  • Interactions: vars(x * y) (main effects + interaction) or vars(x:y) (interaction only; the member-paired interaction \(H_{xz} = \sum_k w_k x_k z_k\))

  • Transformations: vars(I(x^2))

  • Fixed coefficients: vars(fix(x, 1.0) + y)

Note: Numeric literals like 1, 0, or -1 are ignored (no intercept support in mm blocks).

Value

A bml_vars object (list with formula, free, fixed), or NULL if empty.

See also

fix, mm, fn

Examples

if (FALSE) { # \dontrun{
vars(income)
vars(income + education)
vars(income:education)      # member-paired interaction only
vars(x, z)                  # two attributes (e.g. for fn("cov"))
vars(fix(exposure, 1.0) + income)
} # }