Out of the total production in an economy, a big part is market-based, as when you make something and sell it. But a big part is not, as when you make something and don't sell it, but exchange it or use it in some way. Examples of this are home production, cooking, washing, etc, as well as gifts to friends, social service, etc.
More over, the fraction of production that is market-based probably changes over the business cycle. For example, suppose that, in a recession, I agree to cook for my neighbor every other day because we are both unemployed. He cooks for me every other day. In a boom, instead I get a newly created job which pays me 50 dollars a day, and I by a 10 dollar a day meal from my neighbor who now sells me the food he cooks. The economy is only producing 50 dollars more since we used to produce two meals a day and now we are producing the same two meals a day plus 50 dollars. However, because I pay for the 10 in food, it seems the economy is producing 60 dollars more instead of just 50.
Other things that happen in recessions that don't count as output: when you are unemployed, you fix your house, you make art, etc. Maybe businesses give away more goods and services because they have the installed capacity, but not the demand...
Is there a way to measure the size of this effect?