---

     The main goal in this research is to survey and determine the actual structure of the demand function through the BOX-COX consumer goods demand system which includes various forms of demand functions. Using nested and non-nested methods the estimation of consumer demand function is done. Nonlinear seemingly unrelated regressions are also used for the periods of 1982- 2007 via the combined statistics of income groups in urban areas in order to calculate  uncompensated price elasticity and expenditure elasticity associated with the demand function estimate. Results of nested and non-nested tests show that the BCDS and AIDS models are near performance. The elasticity figures resulted from the BCDS and AIDS models have also revealed that food group is an essential one, social affairs (clothing, health, leisure and education) are regarded as almost luxury, and miscellaneous group (transportation and others) is quite luxury. But the group of housing (housing and furniture), in the BCDS model is almost luxury and in the AIDS model considered as essential. The elasticity of demand was confirmed by the demand law and cross elasticity of demand has also shown that the food group compared with the social affairs is considered as supplementary and to the group of housing and miscellaneous is regarded as a substitute. The social affairs group compared with the miscellaneous group is supplementary and to the housing group is a substitute and finally the miscellaneous group is considered as a substitute to the housing group.  

---

Science and technology can have a major role in growth and creating value added of communities. Research and development are important economic issue that cause technological changes and therefore have a significant role in development of technology and increasing production capacities. Although recently developing countries have realized the importance of R&D, their production units are unable to invest more in R&D section. It is also believed that in the early stages of development, the existing technological gap between these countries and technology leaders decrease the success possibility of R&D efforts and as a result, these communities don’t have reasonable technological basis for innovation. So in the early stages of development, in addition to R&D efforts, import of capital goods can also be effective in developing technology and increasing production capacities of developing countries. In this study, the effect of internal R&D capital stock and external capital stock on value added of the Iranian medium and large industries is investigated over the period of 1994-2007 by applying panel data approach. The results indicate that internal and external capital stock, human capital and internal R&D capital stock have a significant and positive effect on added value of the Iranian medium and large industries during the mentioned period. The research findings have also revealed that although the number of labor force has a positive impact on added value of these industries, it is not statistically significant.