# Carbon & Cashmere BTC-ETH Cointegration Analysis

> Carbon & Cashmere BTC-ETH Cointegration Analysis is a paid API for AI agents from api.carbon-cashmere.de, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Returns statistical cointegration analysis between BTC and ETH including Engle-Granger test results, z-score spread, beta coefficient, and mean-reversion half-life over a 90-day lookback.

## Facts

- Endpoint: GET https://api.carbon-cashmere.de/v1/cointegration/BTC-ETH
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/carbon-cashmere-btc-eth-cointegration-analysis-e156fd55
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_cgjkTCbjf726SWjOvFkiS

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 carbon-cashmere-btc-eth-cointegration-analysis-e156fd55
```

Example prompt: Pull the latest cointegration analysis for BTC-ETH — I want to know if they're statistically cointegrated at the 5% level, what the current spread z-score is, and how many days the half-life of mean reversion is.

## When to prefer this

Use this endpoint when building pairs trading strategies, statistical arbitrage systems, or quantitative research tools that need to assess the long-run equilibrium relationship between BTC and ETH. Prefer this over general price endpoints when you specifically need cointegration statistics, spread z-scores, or mean-reversion half-life for the BTC-ETH pair rather than raw prices or trend signals.

## Known failure modes

- Endpoint may return stale data if upstream price feeds are delayed
- Invalid or unsupported pair symbol returns an error
- Payment not included or insufficient USDC balance results in 402 Payment Required
- Rate limiting may apply under high request volume
- Network timeout if crypto data source is temporarily unavailable

## How this service works

Professional crypto market intelligence. Real-time prices, signals, and market scoring.

## Output

A JSON object containing: whether BTC-ETH is cointegrated at 5% and 10% significance levels, Engle-Granger test statistic and p-value with critical values, current spread value and z-score, beta coefficient, ADF p-value for mean reversion, and estimated half-life in days over a 90-day lookback window.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "base": "BTC",
  "pair": "BTC-ETH",
  "_meta": {
   "disclaimer": "Informational research data only — not investment advice."
  },
  "quote": "ETH",
  "spread": {
   "current": 0.023,
   "zscore_current": 1.42,
   "beta_coefficient": 0.89
  },
  "engle_granger": {
   "p_value": 0.012,
   "test_statistic": -3.42,
   "critical_values": {
    "5pct": -3.38
   }
  },
  "lookback_days": 90,
  "mean_reversion": {
   "adf_p_value": 0.018,
   "half_life_days": 4.2
  },
  "is_cointegrated_at_5pct": true,
  "is_cointegrated_at_10pct": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/carbon-cashmere-btc-eth-cointegration-analysis-e156fd55/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)