[Limdep Nlogit List] Dependent Variable Blanks - Double Hurdle Model?

[Christopher McIntosh]

Hello All,

I have CVM survey data and have a problem. Many of the returned surveys 
list a blank for the value of the dependent variable (willingness to 
pay). Other WTP values include zero and positive numbers.

I was informed it is not correct to skip the blanks and they cannot be 
considered zeros so they should be thought of as protest bidders.

Is a double hurdle model appropriate in this case?

I greatly appreciate any modeling advice and how it might be 
implemented in LimDep.

Thanks,

Chris

Christopher McIntosh
Assistant Professor
Department of Economics
SBE 165, Room 171
Duluth, MN, 55812
218-726-8408
cmcintos at d.umn.edu