Gigatrees Blog

Reliability Assessments

Reliability Assessments

When publishing a family tree it is useful for visitors to be able to quickly and accurately assess the validity of the claims being made. Gigatrees automatically calculates the reliability assessment for every claim using several pieces of data including, the source category defined for the referenced sources, the source reference quality (QUAY) defined within the source references for the claim, and the source type defined within the source itself. Gigatrees will display the calculated reliability assessment alongside each claim. Gigatrees also supports manually setting the reliability assessment for claims.

Gigatrees defines several levels of reliability.

"unsupported", "estimated", "unreliable", "uncertain", "proposed", "reported", "supported", "probable", "certain", "questionable", "proven" and "impossible".

When multiple sources are referenced for a claim, the source with the best quality is used. If no source reference is found for a claim, the reliability assessment will be set to unsupported. If a source reference is found for a claim, but no source or source reference quality is defined, the reliability assessment will be set to uncertain. If the claim is an estimated (calculated) birth year, the reliability assessment will be set to estimated.

On occasion, the calculated reliability assessment may be inappropriate for the claim being made. This can be caused by improper source categorization or failure to reference all the available sources. It can also be caused by a reliable source making a unreliable claim. To override these, Gigatrees supports setting the reliability assessment manually by adding the _PROOF tag to any claim.

0 @I1@ INDI
1 BIRT
2 DATE 1 JAN 1900
2 _PROOF proven

Overriding reliability assessments is the only method for directly indicating that a claim is impossible.

The reliability assessment strings are translatable so that you can use strings in your own language.

When displayed, claims always show the "best" assessment, which implies an order of precedence. In general the order of precedence always degrades from the most certain to the least certain. As shown in the table below, there are four GEDCOM data fields that affect order, the reliability assessment override field (_PROOF) described above, the presence of a source reference (SOUR@) for the claim, the source category (_QUAL), and the source reference quality (QUAY) as defined in the GEDCOM standard. Note that not all of the defined reliability assessment strings described above will be automatically determined, but can still be set using the reliability assessment override tag.

To prevent Gigatrees from making exaggerated reliability assessment determinations, sources that contain multiple types of evidence, should set the source category to the quality associated with the least reliable evidence. You can also break up your source into multiple sources, one for each type of evidence.

In the table below, an "x" indicates that a field must be present. An empty field indicates the the value of the field has less precedence or does not matter.

_PROOF      SOUR@  category    type     QUAY  reliability
------ ---- -------- ---- ---- ---------
estimated [calculated]
impossible impossible
[value] [value]
x 0 questionable
x dna proven
x 3 certain
x primary certain
x original certain
x 2 probable
x secondary probable
x transcript probable
x copy probable
x abstract probable
x research supported
x memoir reported
x 1 proposed
x derivative proposed
x unknown uncertain
x unreliable unreliable
x [various]
x uncertain
unsupported

When there is no other information available to determine the reliability assessment, Gigatrees makes one last ditch effort by looking at the source's type (@SOUR.TYPE or @SOUR._TYPE) field. This is a non-standard GEDCOM field, but is used by several popular genealogy applications. The Source Type configuration option can be used to define source types, and which source category will be associated with which type of source. Valid source categories names must be used.

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