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Question about glm family in R

When using glm() in R, is family = "binomial" the same as family = binomial? Are they interchangeable and producing the same results? I am looking at a binary classification problem.

Solution

  • The two commands glm(..., family="binomial") (1) and glm(... , family=binomial) (2) are the same (they will always give the same results).

    You can see this from the R code of glm on lines 7-8:

      7:  if (is.character(family)) 
  8:    family <- get(family, mode = "function", envir = parent.frame())
  9:  if (is.function(family)) 
  10:   family <- family()

    Version (1) specifies the family as a character string, which gets converted to a function using get(). This is now in the same form as version (2).

    is.function(binomial)
[1] TRUE

is.function(get("binomial", mode = "function", envir = parent.frame()))
[1] TRUE