unsupervised
Reliability analysis (Cronbach's alpha)
Assess the internal consistency of multiple items intended to measure one construct.
Requirements
- two or more similarly directed scale items
- a defensible common construct
Avoid when
- multidimensional scales without subscale analysis
- alpha as evidence of validity
Formula
α = k/(k−1) · [1 − Σσᵢ²/σ_total²]
Interpretation
Alpha summarizes item covariance; it does not establish unidimensionality or validity.
Worked example
Assess the internal consistency of items intended to form one scale.
Open example datasets