# Certainty Index

The Certainty Index is an attribute of data about a person as a special indicator that can be evaluated for a person record only.

Each reference to a source in a person record has a specific certainty level of mention for that person in the source. Certainty level can have the following values:

- Unreliable evidence or estimated data (certainty is 25%).
- Questionable reliability of evidence (certainty is 50%).
- Secondary evidence, data officially recorded sometime after event (certainty is 75%).
- Direct and primary evidences, or dominance of evidences (certainty is 100%).

While you are researching and viewing some information, the certainty level shows you how much you can trust that information. It is better to set "Questionable reliability of evidence" if a source document had blots or was damaged and could not be read with confidence. This can prevent you from making false conclusions.

If a reference to a source has no certainty level specified in the database, it is interpreted by the program as "Unreliable evidence or estimated data" when calculating the Certainty Index.

The Certainty Index is evaluated automatically for each person based on certainty level (as the weighted arithmetic mean). You can view the Certainty Index in a statistics module for analysis of mean values or in tree diagrams for pictorial presentation. The index is evaluated using all references to sources, specified in both person record and all materials and events.

In the settings dialog "Service\Options", on the "Common" tab, there is a separate option "Certainty assessment algorithm", which allows you to change the calculation algorithm. Possible options: weighted average, simple average, minimum, maximum.

See also: Personal records, Source records, Trees, Options.