Identify the unit
Ask whether the record concerns candidacies, individual people, votes, elected outcomes, seats or institutional members. These are different units. A person may participate in several electoral contexts, so entries cannot automatically be counted as unique individuals.
Read the label alongside the office and electoral level. A presidential contest, a parliamentary chamber and a municipal council should not be combined simply because they belong to the same country.
Check the period and coverage
An election result describes a particular contest. A membership snapshot describes an institution at a reference date. Historical comparison needs consistent definitions and appropriate periods. Missing evidence is not a documented zero.
Look for the number of eligible records, the years covered and any stated limitations. A source collection may be useful without describing every election or participant.
Follow the calculation
For a percentage, identify the numerator and denominator. Check that they refer to the same population and period. Percentages from different elections should not be added. National totals should not be counted again through included regional components.
Open the source reference before relying on a headline figure. Keep its publisher, publication date and reporting scope with any note or citation you make. This preserves the context needed by the next reader.