Classification of period of construction

Usage

The period of construction categories can be collapsed to form larger categories to suit a particular data set or analytical purpose. The collapsed categories should be created by combining entire period of construction categories, respecting the category boundaries of this classification.

In cases where a survey year does not match the most recent year of the final category in the classification, the year of the survey itself can replace the year indicated in the classification. For example, for surveys conducted in 2020, the last category would be '2016 to 2020'.