I am new for panel data analysis but trying for my master thesis.I am doing a gravity model analysis for sri lankalanka bilateral fish trade using eviews.I have prepared excel sheet and found there are 391cross sections and have data for 17years.problem is there are many missing values in independent variables.and also zero trades in dependent variable as well.eviews omit all zeros and missing values when analysisng.I amresearcher afraid though originally I have 391 panels eviews results shows only 256 panels.will it affect to the results and give me a wrong interpretation of the real picture??