Cronbach's alpha reliability API

Computes Cronbach's alpha internal-consistency reliability from a respondents x items score matrix, plus standardized alpha, item variances, mean inter-item correlation, and alpha-if-item-dropped diagnostics. Answers 'What is the reliability of my scale?', 'Which item is dragging down my alpha?'.

Price$0.06per request

MethodPOST

Route/v1/stats/cronbach-alpha

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

psychometricsreliabilitycronbachalphainternal-consistencyscalesurveytest-theory

API URLhttps://x402.hexl.dev/v1/stats/cronbach-alpha

Integration docs

Example request

{
  "matrix": [
    [
      3,
      4,
      3,
      4
    ],
    [
      5,
      5,
      4,
      5
    ],
    [
      2,
      3,
      2,
      2
    ],
    [
      4,
      4,
      4,
      3
    ],
    [
      3,
      3,
      3,
      4
    ],
    [
      5,
      4,
      5,
      5
    ],
    [
      1,
      2,
      2,
      1
    ],
    [
      4,
      3,
      4,
      4
    ],
    [
      3,
      4,
      3,
      3
    ],
    [
      2,
      2,
      3,
      2
    ]
  ]
}

Example response

{
  "alpha": 0.935644,
  "standardizedAlpha": 0.939613,
  "nItems": 4,
  "nRespondents": 10,
  "itemVariances": [
    1.56,
    0.84,
    0.81,
    1.61
  ],
  "sumItemVariances": 4.82,
  "totalScoreVariance": 16.16,
  "meanInterItemCorrelation": 0.795499,
  "alphaIfItemDropped": [
    0.873077,
    0.945167,
    0.926597,
    0.904821
  ],
  "interpretation": "excellent internal consistency"
}

Input schema

{
  "type": "object",
  "required": [
    "matrix"
  ],
  "properties": {
    "matrix": {
      "type": "array",
      "items": {
        "type": "array",
        "items": {
          "type": "number"
        }
      },
      "description": "respondents (rows) x items (cols) score matrix",
      "examples": [
        [
          [
            3,
            4,
            3,
            4
          ],
          [
            5,
            5,
            4,
            5
          ],
          [
            2,
            3,
            2,
            2
          ]
        ]
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}