Research and tracking
SERP Sensor methodology
How the public daily volatility index is collected, calculated, budgeted, and limited.
SERP Sensor methodology
The SERP Sensor is a shared public index of observed search-result movement. It is not a personal rank tracker, a forecast, or a monitor for your own keyword set.
<!-- docs-truth: metric=none; unit=none-public-operator-funded; cache-hits=not-applicable; refund=not-applicable; cadence=daily-utc; estimates=none-observed-displacement -->Fixed basket and cadence
RankMeFast checks the same 200 fixed US-English keywords once per UTC day: 20 keywords in each of 10 categories. For every keyword it keeps the first 20 unique public HTTP or HTTPS result URLs. Users cannot change the keywords, market, language, depth, or collection time.
The categories cover finance, health, travel, technology, retail, entertainment, local services, education, real estate, and automotive. The fixed basket makes one day comparable with the next; it does not represent every search or location.
How the index is calculated
For one keyword, each result's current rank is compared with its previous rank. A result missing on one day is treated as rank 21. The absolute rank movements across the union of both result sets are added and divided by 420, the maximum displacement for a top-20 set. This produces a value from 0 to 1.
RankMeFast averages the 20 keyword values in a category and scales the result to 0–10, rounded to one decimal place. The composite is the average of the category values that were published that day. The labels describe observed displacement:
| Index | Label |
|---|---|
| 0.0–2.0 | Low |
| above 2.0–4.5 | Routine |
| above 4.5–7.0 | Elevated |
| above 7.0–10.0 | High |
The first complete observation is a baseline and has no numeric change. If only some categories complete, the composite is marked partial. Missing data is not estimated or filled.
Budget and availability
The sensor uses a global operator budget, not a customer allowance. It consumes no account unit, has no customer cache rule, and has no refund because customers are never charged. The collector checks its budget before and during the daily run. A category skipped for budget or collection failure is labeled accordingly.
Public history contains at most the latest 30 stored dates per category. Turning the sensor off returns an unavailable state without exposing the fixed keywords or result URLs.
For customer-run research features and their units, see Pricing.