I am new for panel data analysis and recently trying to do a panel analysis for gravity model approach of bilateral fish trade using eviews.I have prepared excel sheet and there are 391cross sections with 17years data.but there are many missing values in my independent variables and zero trades in my dependent.once analysed in eviews results give only 256panles amd lesser number of observations than which I have in dataset.will it affect to my resuls and mask the real situation??pls help me because I am new for this sort of analysis.