# SignalDesk AI – Sample Variance Calculator

> SignalDesk AI – Sample Variance Calculator is a paid API for AI agents from x402-agent.kariguetoazul.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-13).

Computes the sample variance of a provided array of numeric observations

## Facts

- Endpoint: POST https://x402-agent.kariguetoazul.workers.dev/api/stats/sample-variance?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signaldesk-ai-sample-variance-calculator-ecf4f21f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_OsBfrfmPVL8KsveNkDLSa

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 signaldesk-ai-sample-variance-calculator-ecf4f21f -d '<json body>'
```

Example prompt: Calculate the sample variance for these numbers: 4, 7, 13, 2, 1, 9, 15, 6.

## When to prefer this

Choose this endpoint when you need a quick, paid, serverless sample variance computation without running your own statistical library — especially useful in agent pipelines where deterministic statistical outputs are needed on-demand with micro-payment billing via x402 and no infrastructure setup.

## Known failure modes

- Fewer than 2 values provided — minimum 2 observations required
- Array exceeds 1000 items — maxItems limit enforced
- Individual values exceed ±1e15 magnitude — boundary enforced
- Invalid input types (non-numbers in array) — schema validation error
- Payment failure (x402) — 402 response if USDC payment not attached

## How this service works

Evidence-backed autonomous AI jobs and paid data tools. Queue/D1/cron run outside the chat; free quotas and bounded execution apply.

## Output

Returns a JSON object containing the computed sample variance (using n-1 denominator for unbiased estimation) and the denominator value used in the calculation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "values": {
   "type": "array",
   "items": {
    "type": "number",
    "maximum": 1000000000000000,
    "minimum": -1000000000000000
   },
   "maxItems": 1000,
   "minItems": 2,
   "description": "At least two observations."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "variance": 1,
  "denominator": 2
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signaldesk-ai-sample-variance-calculator-ecf4f21f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-agent.kariguetoazul.workers.dev](https://www.zero.xyz/host/x402-agent.kariguetoazul.workers.dev/llms.txt)