In the study, the demand for potatoes (fresh potatoes and frozen
potatoes), pea (fresh peas and frozen peas), green beans (fresh
green beans and frozen green beans), strawberry (fresh strawberry
and frozen strawberry) and cherry (fresh cherry and frozen cherry)
were estimated using the Heckman two-stage demand model
considering the cases where there was zero observation. The
Heckman model eliminates the bias caused by the censorship in
regression coefficients. Sample selection bias occurred in a large