Compute Cronbach's alpha coefficient of reliability from survey data. The formula is equation (2) of Cronbach (1951) only with design-based estimates of the variances.

`svycralpha(formula, design, na.rm = FALSE)`

## Arguments

- formula
One-sided formula giving the variables that make up the total score

- design
survey design object

- na.rm
`TRUE`

to remove missing values

## References

Cronbach LJ (1951). "Coefficient alpha and the internal structure of tests". Psychometrika. 16 (3): 297-334. doi:10.1007/bf02310555.

## Examples

```
data(api)
dstrat<-svydesign(id = ~1, strata = ~stype, weights = ~pw, data = apistrat,
fpc = ~fpc)
svycralpha(~ell+mobility+avg.ed+emer+meals, dstrat)
#> *alpha*
#> 0.6386731
```