# Siliq SPC Analytics

> Siliq SPC Analytics is a paid API for AI agents from compute.siliq.io, paid per call via x402, $0.01/call, status down (last checked 2026-09-15).

Computes Statistical Process Control metrics including control limits, Western Electric rule violations, and process capability indices (Cp, Cpk) for a data series.

## Facts

- Endpoint: POST https://compute.siliq.io/analytics/spc
- Price: $0.01/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/compute-siliq-io-58210822
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Jmsq_9wX6SFS9oFA2Nthc

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 compute-siliq-io-58210822 -d '<json body>'
```

Example prompt: Run an SPC analysis on this dataset of 50 bottle-fill measurements (target 500ml, LSL 495ml, USL 505ml) — give me the control limits, flag any Western Electric rule violations, and calculate the Cp and Cpk.

## When to prefer this

Choose this endpoint when you need a complete SPC analysis bundle — control limits, Western Electric rule checks, and capability indices — in a single API call, rather than computing each separately. Ideal for quality engineers automating process monitoring pipelines or agents performing on-demand manufacturing quality assessments.

## Known failure modes

- Insufficient data points for reliable control limit calculation (too few samples)
- Missing or invalid specification limits preventing Cp/Cpk calculation
- Non-numeric or malformed data series returning a 400 validation error
- Data with extreme outliers skewing control limit estimates
- Payment failure via x402 protocol returning 402 status

## Output

Returns computed UCL/LCL control limits, a list of Western Electric rule violations with their indices, and process capability indices Cp and Cpk indicating whether the process is both stable and capable relative to specification limits.

## Example request

```json
{
 "lsl": 45,
 "usl": 55,
 "data": [
  45.2,
  46.1,
  47.3,
  48.5,
  49.1,
  50.2,
  51,
  50.8,
  49.9,
  48.7,
  47.5,
  46.8,
  47.2,
  48.1,
  49.3,
  50.5,
  51.2,
  50.9,
  49.8,
  48.6,
  47.4,
  46.9,
  47.1,
  48,
  49.2,
  50.4,
  51.1,
  50.7,
  49.7,
  48.5
 ],
 "chartType": "xbar-r",
 "subgroupSize": 5
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "properties": {}
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/compute-siliq-io-58210822/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from compute.siliq.io](https://www.zero.xyz/host/compute.siliq.io/llms.txt)