What is the difference between a shift in demand? (an increase or decrease in demand) and a change in the quantity demanded?? What do these concepts have to do with endogenous and exogenous variables? Can we say that a change in the quantity demanded? is due to a shift in an exogenous variable?

A shift in demand refers to a decrease or an increase in demand resulting from other factors other than the own price. Some of the factors that cause a shift in demand include the price of related commodities, tastes, and income levels. On the contrary, a change in quantity demanded is the movement along the demand curve arising from the change in own price of a product.

A shift in demand is caused by exogenous such as income levels, tastes and preferences, and expectations. On the contrary, a change in quantity demanded is caused by endogenous variable, that is, price.

No. Change in quantity demanded is due to a shift in an endogenous variable.