What is the role of an agricultural economist?

How do economist determine autonomous spending of a country and what role does it play in economic cycles?

• I was in my macroeconomic theory class and was learning about the the AS-AD model. We were told about a level of spending that is always there when income is zero, this is autonomous spending by the way-hence this is my working definition-. But really, that will never happen even in recessions. So in determining the impact of policy on an economy autonomous spending become a source of multiplier. How is this determined beforehand?....answers are appreciated.

• Answer:

  When it comes to draw the economic policy in a counrty an econometric  model, perhaps a conmplex one with many variables, is constructed. We give a simple example that is pretty close to the true although not very good specificated. The econometric model will be the following: C= a + bY Where C is the consume what we want to measure, a is the constant term, b is the slop coefficient and Y is the Income or the per capita GDP. We expect the coefficient b to be possitive as the economic theory indicates. So, if we draw the model on the Y and X axises, given the positive b, the regression line is going to cut the Y axis most likely beyond zero. Your hypothesis that the income is never going to be zero for real is true but some of the observations we used in the model are referred to people with very low income. An econometric regression model in most of the cases is used to make predictions. Now, recall the positive slop and the positive cut at the Y axis. Is true that income is never going to be zero, but if we set it equal to zero by hand in the equation, all we have is just C= a +0 => C= a. So, the constant term a is actually the consuption in the hypothetical zero income. We call this autonomous spending as you said because even if your income is zero (in some cases it's true for some people with no job, no family income etc) you still have the need for some spending for basic things that are critical for your life.