en THE DEVELOPMENT OF THE COMPOSED PROBABILITY MODEL TO ESTIMATE THE RATE OF HOUSEHOLD TRIP PRODUCTION (CASE STUDY OF KARAJ CITY) Research Paper Research Paper The purpose of the present study, is proposing a more flexible model comparing with linear regression model, to estimate the rate of household trip production and its prediction in the�project horizon. For this purpose, a combined model composed of poission distribution and the possible distribution of A. in the form of negative binominal distribution are used. Then the proposed model was conducted on a real case (Karaj City). Then the result of model processinghas been compared to .the real observation in the peak hours in Karaj city. Trip household� production, Linear regression distribution, Peak �hour, Polssion distribution, Negative binomial distribution, Socio,Economic characteristics, Auto ownership, Household size, Household income 72 77 http://ijce.iust.ac.ir/browse.php?a_code=A-10-591-1&slc_lang=en&sid=1 KHAKI A.M. 180031947532846001999 180031947532846001999 Yes MOAYEDFAR R. 180031947532846002000 180031947532846002000 No