How is the Sensor score calculated?
We check the search results for a fixed set of keywords on a daily basis and measure how much has changed at the end of the day.
For each keyword, we do a per-item comparison of "today’s" results vs "yesterday’s" results. We measure how much has changed in a day using Levenshtein distance (as a basis) and normalization.
The total value of the score reflects the total search volatility for the day.