Effect-size conversions API

Converts between common effect-size metrics — Cohen's d, Pearson r, odds ratio and eta-squared — using the standard formulas (with an optional sample-size adjustment for d↔r). Answers 'How do I convert Cohen's d to r or an odds ratio?', 'What is the equivalent effect size in another metric?'.

Price$0.04per request

MethodPOST

Route/v1/stats/effect-size-convert

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

statisticseffect-sizecohens-dpearson-rodds-ratioeta-squaredconversionmeta-analysis

API URLhttps://x402.hexl.dev/v1/stats/effect-size-convert

Integration docs

Example request

{
  "from": "d",
  "value": 0.5
}

Example response

{
  "from": "d",
  "inputValue": 0.5,
  "balanced": true,
  "cohensD": 0.5,
  "pearsonR": 0.242536,
  "oddsRatio": 2.476632,
  "eta2": 0.058824,
  "rating": "medium",
  "interpretation": "Converted to Cohen's d=0.5 (medium); r=0.2425, OR=2.4766, η²=0.0588."
}

Input schema

{
  "type": "object",
  "required": [
    "from",
    "value"
  ],
  "properties": {
    "from": {
      "type": "string",
      "enum": [
        "d",
        "r",
        "oddsRatio",
        "eta2"
      ]
    },
    "value": {
      "type": "number",
      "examples": [
        0.5
      ]
    },
    "n1": {
      "type": "integer"
    },
    "n2": {
      "type": "integer"
    }
  }
}

Output schema

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