Sample size calculator

Open Sample size calculator on Happytails.ai. This view has the same page content and links, with explicit tool capabilities. Read the processing notes before using a tool.

Tool capabilities

{
  "id": "sample-size-calculator",
  "category": "calculators",
  "built": true,
  "requirements": "Normal-approximation precision planning, not a power analysis. Confidence 50–99.99%; finite populations up to one billion. Expected proportions must be strictly between 0 and 100%. A low expected event count triggers a warning. Invitations can exceed the available population and are flagged.",
  "implementation": {
    "fields": [
      {
        "key": "method",
        "label": "Plan an estimate of",
        "value": "Proportion",
        "type": "select",
        "values": [
          "Proportion",
          "Mean (known planning SD)"
        ]
      },
      {
        "key": "confidence",
        "label": "Confidence level (%)",
        "value": 95,
        "type": "number",
        "min": 50,
        "max": 99.99,
        "step": "any"
      },
      {
        "key": "margin",
        "label": "Margin of error",
        "value": 5,
        "type": "number",
        "min": 1e-08,
        "max": 1000000000000,
        "step": "any",
        "help": "For a proportion, use percentage points: 5 means ±5 points. For a mean, use the measurement units."
      },
      {
        "key": "proportion",
        "label": "Expected proportion (%)",
        "value": 50,
        "type": "number",
        "min": 0.001,
        "max": 99.999,
        "step": "any",
        "help": "Use 50% when unsure. Very rare outcomes may make normal-approximation planning unreliable.",
        "showWhen": {
          "method": [
            "Proportion"
          ]
        }
      },
      {
        "key": "sd",
        "label": "Planning standard deviation",
        "value": 10,
        "type": "number",
        "min": 1e-12,
        "max": 1000000000000,
        "step": "any",
        "showWhen": {
          "method": [
            "Mean (known planning SD)"
          ]
        }
      },
      {
        "key": "population",
        "label": "Finite population (optional)",
        "value": "",
        "type": "number",
        "min": 2,
        "max": 1000000000,
        "step": 1,
        "required": false
      },
      {
        "key": "designEffect",
        "label": "Design effect",
        "value": 1,
        "type": "number",
        "min": 0.01,
        "max": 1000,
        "step": "any"
      },
      {
        "key": "responseRate",
        "label": "Expected response rate (%)",
        "value": 100,
        "type": "number",
        "min": 0.01,
        "max": 100,
        "step": "any"
      }
    ],
    "note": "Estimate required completed responses for precision, not hypothesis-test power. Population correction assumes random sampling without replacement. Response-rate planning does not guarantee enough responses.",
    "input": false,
    "live": true,
    "presentation": "metrics",
    "background": false,
    "inputMaxLength": 1000000,
    "inputErrorCode": "STAT_SIZE",
    "experience": {
      "automatic": true,
      "single": false,
      "inputMaxLength": 1000000,
      "inputMode": "text",
      "label": "Your text",
      "placeholder": "Type or paste your input…",
      "help": "Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.",
      "helpParts": [
        "Change the input or settings to update your result.",
        "Results update as you type.",
        "Up to 1,000,000 characters."
      ],
      "action": null
    },
    "mode": "automatic",
    "interactive": false
  },
  "execution": "Browser interface",
  "api": null,
  "browser_agent": {
    "supported": true,
    "name": "run_current_tool",
    "discovery": "WebMCP on the human page in a supporting browser",
    "verification": "See audit/API-AUDIT.md; availability is not verification"
  }
}

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