# Carbon Cashmere Cointegration Test API

> Carbon Cashmere Cointegration Test API is a paid API for AI agents from api.carbon-cashmere.de, paid per call via x402, $0.12/call, status unknown (last checked 2026-09-14).

Runs Engle-Granger cointegration test and Augmented Dickey-Fuller on a crypto pair spread, returning statistical test results, spread analytics, and mean-reversion half-life for pairs trading research.

## Facts

- Endpoint: GET https://api.carbon-cashmere.de/v1/cointegration/:pair
- Price: $0.12/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/api-carbon-cashmere-de-25f91965
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qHys1dINW8BqMy496ua5A

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 api-carbon-cashmere-de-25f91965
```

Example prompt: Can you run a cointegration test on BTC-ETH — I want to know if they're statistically cointegrated, what the current z-score and spread beta are, and how many days the spread takes to mean-revert?

## When to prefer this

Choose this endpoint when you need rigorous statistical validation of a crypto pairs-trading hypothesis — specifically Engle-Granger cointegration with ADF confirmation and mean-reversion speed (OU half-life). Prefer it over simple correlation checks when you need p-values, critical value thresholds, and actionable z-scores for entry/exit signals in a statistical arbitrage strategy.

## Known failure modes

- Invalid pair format (not uppercase BASE-QUOTE) returns 400 validation error
- Pair not supported or insufficient historical data returns 404 or empty result
- Spread is non-stationary — half-life field may be absent or null
- Payment not provided or insufficient USDC returns 402 Payment Required
- Rate limiting or upstream data unavailability returns 503

## How this service works

Engle-Granger cointegration test + Augmented Dickey-Fuller on spread + half-life of mean reversion. Pair format: BASE-QUOTE (e.g. /v1/cointegration/BTC-ETH). Returns test_statistic, p_value, critical values (1/5/10 pct), is_cointegrated flags, spread analytics (beta coefficient, current z-score, mean/std), and OU half-life in days if stationary. Statistical pairs-trading research tool. Informational research data — not investment advice.

## Output

Returns Engle-Granger test statistic and p-value, critical values at 1%/5%/10% thresholds, is_cointegrated boolean flags, spread analytics (beta coefficient, current z-score, mean, std), and the Ornstein-Uhlenbeck half-life in days if the spread is stationary.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/api-carbon-cashmere-de-25f91965/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.carbon-cashmere.de](https://www.zero.xyz/host/api.carbon-cashmere.de/llms.txt)