why Economics considered as a science

Economics is considered as a science because of the following reasons:

It is based on systematic study of knowledge or facts: All the theories and facts related with both micro and macro economics are systematically collected, classified and analysed.
It develops correlationship between cause and effect: For example, supply is a positive function of price, i.e., change in price is cause but change in supply is effect.
All its laws are universally accepted: These are the law of demand, law of supply, law of diminishing marginal utility, etc.
All its laws and theories are tested and based on experiments: e.g. mixed economy is an experimental outcome between capitalist and socialist economies
It can make future predictions: Economics predicts what may happen in the future if human beings adopt certain behaviour.
It has a scale of measurement: According to Prof. Marshall, ‘money’ is used as the measuring rod in economics. However, according to Prof. A.K. Sen, Human Development Index (HDI) is used to measure economic development of a country.