The three main modes of economic investigation along with their brief description are as follows:

• Empirical Investigation: Taking in the record, some statistical data about the world, which helps to improve the economic stability is referred to as Empirical Investigation.
• Theoretical Investigation: When we collect data based on some thinkable and correct deductions about the world, such type of investigation is referred to as Theoretical Investigation.
• Historical Investigation: Based on past incidents, the investigation in which the data (about past) is collected for economical activities, such an investigation is referred to as Historical Investigation.