I am currently doing a study on the impact of a change in agriculture taxes on agriculture output.
I want to compare output (volume in $) data for years 2013-2014-2015-2016-2017 in different crop categories (maize, sugar cane, cotton and Tobacco) and find a correlation between tax rate and output.
In 2015 the tax went from 10% to 32%.
What method do you suggest I approach this?
Very weak in stats would appreciate any help.