# Alpha: Reliability analysis (Cronbach's alpha and McDonald's omega). In bruceR: Broadly Useful Convenient and Efficient R Functions

 Alpha R Documentation

## 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()`.

`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.