FSA {rFSA}

FSA: Feasible Solution Algorithm

Description

A function using a Feasible Solution Algorithm to find a set of feasible solutions for a statistical model of a specific form that could include mth-order interactions (Note that these solutions are optimal in the sense that no one swap to any of the variables will increase the criterion function.)

Usage

FSA(
  formula,
  data,
  fitfunc = lm,
  fixvar = NULL,
  quad = FALSE,
  m = 2,
  numrs = 1,
  cores = 1,
  interactions = T,
  criterion = AIC,
  minmax = "min",
  checkfeas = NULL,
  var4int = NULL,
  min.nonmissing = 1,
  return.models = FALSE,
  fix.formula = NULL,
  ...
)

lmFSA(...)

glmFSA(...)

Arguments

formula

an object of class "formula" (or one that can be coerced to that class): a symbolic description of the model to be fitted.

data

a data frame, list or environment (or object coercible by as.data.frame to a data frame) containing the variables in the model.

fitfunc

the method that should be used to fit the model. For Example: lm, glm, or other methods that rely on formula, data, and other inputs.

fixvar

variable(s) to fix in the model. Usually a covariate that should always be included (Example: Age, Sex). Will still consider it with interactions. Default is NULL.

quad

Include quadratic terms or not. Logical.

m

order of terms to include. If interactions is set to TRUE then m is the order of interactions to be considered. For Subset selection (interaction=F), m is the size of the subset to examine. Defaults to 2.

numrs

number of random starts to perform.

cores

number of cores to use while running. Note: Windows can only use 1 core. See mclapply for details. If function detects a Windows user it will automatically set cores=1.

interactions

whether to include interactions in model. Defaults to TRUE.

criterion

which criterion function to either maximize or minimize. For linear models one can use: r.squared, adj.r.squared, cv5.lmFSA (5 Fold Cross Validation error), cv10.lmFSA (10 Fold Cross Validation error), apress (Allen's Press Statistic), int.p.val (Interaction P-value), AIC, BIC.

minmax

whether to minimize or maximize the criterion function

checkfeas

vector of variables that could be a feasible solution. These variables will be used as the last random start.

var4int

specification of which variables to check for marginal feasiblilty. Default is NULL

min.nonmissing

the combination of predictors will be ignored unless this many of observations are not missing

return.models

bool value to specify whether return all the fitted models which have been checked

fix.formula

...

...

other arguments passed to fitfunc.

Value

matrix of results

Functions

• FSA: find best set of variables for statistical models

• lmFSA: alias for FSA(fitfunc=lm,...)

• glmFSA: alias for FSA(fitfunc=glm,...)

Examples

N <- 10 #number of obs
P <- 100 #number of variables
data <- data.frame(matrix(rnorm(N*(P+1)), nrow = N, ncol = P+1))

sln <- FSA(formula = "X101~1", data = data, cores = 1, m = 2,
interactions = FALSE, criterion = AIC, minmax = "min",
numrs = 10)
sln