> ## Documentation Index
> Fetch the complete documentation index at: https://docs.quantoraresearch.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Derived analytics

> Series we compute from public inputs, and how to tell them apart.

Some of the most useful series are not published anywhere. They are computed from
inputs that are, and every one is marked `sourceTier: "financialdatapi_derived"` so it
is never mistaken for a publisher's own figure.

## What is computed

| Series                           | Built from                         |
| -------------------------------- | ---------------------------------- |
| Real policy rate                 | Policy rate minus year on year CPI |
| Curve spreads                    | Sovereign yields at two tenors     |
| Surprise indices                 | Releases against consensus         |
| FX returns, volatility and trend | Reference rate history             |
| Positioning percentiles          | COT history                        |
| Company multiples                | Filed statements and market data   |

## Calling it

Identical to any other series. There is no separate endpoint, because a derived series
is an observation like any other.

<CodeGroup>
  ```bash cURL theme={"dark"}
  curl -H "x-api-key: $QUANTORA_API_KEY" \
    "https://api.financialdatapi.com/observations/latest?country=USA&indicator_id=real_policy_rate"
  ```

  ```python Python theme={"dark"}
  derived = requests.get(
      "https://api.financialdatapi.com/observations/latest",
      params={"country": "USA", "indicator_id": "real_policy_rate"},
      headers={"x-api-key": KEY},
  ).json()["data"]
  ```
</CodeGroup>

To see only publisher figures, filter on tier:

```python theme={"dark"}
official = [r for r in rows if r["sourceTier"] != "financialdatapi_derived"]
```

## Inherited constraints

A derived series is only as good as its inputs, and it inherits their limits rather
than smoothing over them.

**Availability.** A real policy rate needs both a policy rate and a CPI print. Where
either is missing, the derived series is missing too, not estimated.

**Timing.** The derived row is dated to the **later** of its inputs. A real rate
combining a daily policy rate with a monthly CPI moves at monthly frequency.

**Revisions.** When an input is revised, the derived series is recomputed. Store
`releaseDate` for point in time work.

<Note>
  Eligibility for derived series is assessed on the derived row itself, not inherited
  from its inputs. A derived row built from stale inputs is marked stale.
</Note>