Tip: Are you a non-native English speaker? I have just finished creating a 
Web AppThe economy is, according to the Oxford Learner’s Dictionary, “the relationship between production, trade and the supply of money in a particular country or region”, so we can say, for example:
The economy is in recession.
Economics is a science that studies economies and develops possible models for their functioning, e.g.
He studied economics at the LSE (London School of Economics).
Economic, without an “s”, is an adjective meaning “connected with economy”, e.g.
The economic growth is very slow.
Economical, on the other hand, carries a somewhat figurative meaning of “not requiring too much of something” (such as money, space, time, etc.), e.g.
That placement of furniture exhibits a very economical use of space.
