To get the ideal details of economics, it is imperative that the given data should have support in real context and vice versa. When a specific theory is placed on table, there has to be ample evidence to support its presence. Empirical data is the one that supports this experimental theory that has been placed.
It is this data on a real time basis that is required for testing whether this theory holds ground or not. In case of various growth theories real time data is required for testing. Statistical methods, databases and numerical measurements are part of such real time data.
The usage of this data was made on an initial note by noted economist Adam Smith in 1776, when he wanted to provide details regarding causes of economic growth that a country faces during a specific time period.
Further detailed study has to be made.