# Cohen's d Effect Size Calculator

> Cohen's d Effect Size Calculator is a paid API for AI agents from kihustle.tech, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Computes Cohen's d effect size statistic by comparing two numeric data groups

## Facts

- Endpoint: POST https://kihustle.tech/bot-bazaar/api/v1/effect-size-cohens-d
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cohen-s-d-effect-size-calculator-1331256d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fhFSarzv9GMcy0JaBgNiq

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability cohen-s-d-effect-size-calculator-1331256d -d '<json body>'
```

Example prompt: Calculate Cohen's d effect size for these two groups — group A is [23, 25, 28, 22, 30] and group B is [18, 20, 19, 21, 17] — and tell me how large the effect is.

## When to prefer this

Use this endpoint when you need a standardized, interpretable measure of practical difference between two numeric groups — particularly for A/B testing, scientific research, or any scenario where statistical significance alone is insufficient and you need to know the magnitude of an effect. Prefer this over raw mean comparison when sample sizes differ or when communicating results to non-technical stakeholders who need a clear 'small/medium/large' framing.

## Known failure modes

- Empty arrays provided for one or both groups — computation fails with no data
- Single-element arrays causing division by zero in standard deviation calculation
- Non-numeric values in the arrays causing parsing errors
- Both groups having zero variance leading to undefined effect size
- Malformed JSON input schema resulting in a 400 error

## How this service works

Kostenlose Guides, Solo-Playbooks und Artikel zu KI, Automation und Side Hustles — für Menschen, die mit echten Systemen online Einkommen aufbauen wollen. Transparent finanziert über faire Affiliate-Links.

## Output

Returns a JSON object containing the computed Cohen's d value and a success status indicator. Cohen's d represents the standardized mean difference between two groups, where values around 0.2 are considered small, 0.5 medium, and 0.8 or above large effects.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "group_a": {
   "type": "array",
   "items": {
    "type": "number"
   }
  },
  "group_b": {
   "type": "array",
   "items": {
    "type": "number"
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": "processed",
  "status": "success"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cohen-s-d-effect-size-calculator-1331256d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from kihustle.tech](https://www.zero.xyz/host/kihustle.tech/llms.txt)