Alpha: Reliability analysis (Cronbach's alpha and McDonald's omega).

In bruceR: Broadly Useful Convenient and Efficient R Functions

Reliability analysis (Cronbach's α and McDonald's ω).

Description

An extension of psych::alpha() and psych::omega(), reporting (1) scale statistics (Cronbach's α and McDonald's ω) and (2) item statistics (item-rest correlation [i.e., corrected item-total correlation] and Cronbach's α if item deleted).

Three options to specify variables:

1. var + items: common and unique parts of variable names (suggested).

2. vars: a character vector of variable names (suggested).

3. varrange: starting and stopping positions of variables (NOT suggested).

Usage

Alpha(
  data,
  var,
  items,
  vars = NULL,
  varrange = NULL,
  rev = NULL,
  digits = 3,
  nsmall = digits
)

Arguments

data	Data frame.
var	[Option 1] The common part across the variables. e.g., "RSES"
items	[Option 1] The unique part across the variables. e.g., 1:10
vars	[Option 2] A character vector specifying the variables. e.g., c("X1", "X2", "X3", "X4", "X5")
varrange	[Option 3] A character string specifying the positions ("starting:stopping") of variables. e.g., "A1:E5"
rev	[Optional] Variables that need to be reversed. It can be (1) a character vector specifying the reverse-scoring variables (recommended), or (2) a numeric vector specifying the item number of reverse-scoring variables (not recommended).
digits, nsmall	Number of decimal places of output. Default is 3.

Value

A list of results obtained from psych::alpha() and psych::omega().

See Also

MEAN, EFA, CFA

Examples

# ?psych::bfi
data = psych::bfi
Alpha(data, "E", 1:5)   # "E1" & "E2" should be reversed
Alpha(data, "E", 1:5, rev=1:2)            # correct
Alpha(data, "E", 1:5, rev=cc("E1, E2"))   # also correct
Alpha(data, vars=cc("E1, E2, E3, E4, E5"), rev=cc("E1, E2"))
Alpha(data, varrange="E1:E5", rev=cc("E1, E2"))

# using dplyr::select()
data %>% select(E1, E2, E3, E4, E5) %>%
  Alpha(vars=names(.), rev=cc("E1, E2"))

bruceR documentation built on March 7, 2023, 5:41 p.m.