# Observed Unit Sales Velocity - Before and After Comparison

> Observed Unit Sales Velocity - Before and After Comparison is a paid API for AI agents from market.datapackvibe.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-15).

Computes and compares retail unit sales velocity (units sold per day) across two time periods to quantify change

## Facts

- Endpoint: POST https://market.datapackvibe.com/x402/assistant-ar-retail-unit-sales-velocity-compare?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/observed-unit-sales-velocity-before-and-after-comparison-fcacc409
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Y-8sJ4RO3GlCdrLeBz13o

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 observed-unit-sales-velocity-before-and-after-comparison-fcacc409 -d '<json body>'
```

Example prompt: Compare my product's unit sales velocity before and after a promotion: before the promo I sold 84 units over 7 days, and after the promo I sold 92.4 units over 7.7 days — give me a before-and-after comparison report.

## When to prefer this

Choose this endpoint when you need a quick, inexpensive ($0.01 USDC) structured comparison of retail unit sales velocity across exactly two time windows using your own supplied figures. It is ideal for evaluating the impact of promotions, price changes, resets, or restocks without needing platform access, live data feeds, or order execution. Prefer alternatives if you need more than 200 records, real-time sales data, or multi-period trend analysis.

## Known failure modes

- Missing required fields (sold_units or observed_days for either period) returns a validation error
- observed_days of 0 is rejected (exclusiveMinimum enforced) to prevent division-by-zero
- Values exceeding 1e12 are outside the allowed range and will be rejected
- Negative sold_units values are rejected (minimum: 0)
- Service may be unavailable if the x402 payment of 0.01 USDC is not successfully processed

## How this service works

Observed unit sales velocity - Before and after comparison: Before and after comparison for Observed unit sales velocity. Supplied retail figures only, up to 200 records. No platform access, live rates or order execution. One of 25 new profiles across 20 shared operations in this industry. 0.01 USDC includes one bounded before and after comparison report.

## Output

A bounded before-and-after comparison report containing the computed unit sales velocity (units per day) for each period, the absolute and/or relative change in velocity, and a structured summary derived from the two supplied retail data points — no live market rates or order execution included.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "after": {
   "type": "object",
   "default": {
    "sold_units": 92.4,
    "observed_days": 7.700000000000001
   },
   "required": [
    "sold_units",
    "observed_days"
   ],
   "properties": {
    "sold_units": {
     "type": "number",
     "default": 84,
     "maximum": 1000000000000,
     "minimum": 0
    },
    "observed_days": {
     "type": "number",
     "default": 7,
     "maximum": 1000000000000,
     "minimum": 0,
     "exclusiveMinimum": 0
    }
   },
   "additionalProperties": false
  },
  "before": {
   "type": "object",
   "default": {
    "sold_units": 84,
    "observed_days": 7
   },
   "required": [
    "sold_units",
    "observed_days"
   ],
   "properties": {
    "sold_units": {
     "type": "number",
     "default": 84,
     "maximum": 1000000000000,
     "minimum": 0
    },
    "observed_days": {
     "type": "number",
     "default": 7,
     "maximum": 1000000000000,
     "minimum": 0,
     "exclusiveMinimum": 0
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/observed-unit-sales-velocity-before-and-after-comparison-fcacc409/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from market.datapackvibe.com](https://www.zero.xyz/host/market.datapackvibe.com/llms.txt)