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The consumption expenditure is a key element of macroeconomic analyses, which accounts for considerable share of aggregate demand in Iran. Any effort for forecasting the future consumption trend is of special importance for policy-makers. In this paper, we specify a consumption model relying on theoretical basics in order to obtain desirable forecasts. On the basis of Duesenberry and Friedman consumption theories, we use genetic algorithm (GA) and particle swarm optimization (PSO) algorithm to simulate Iranians consumption during 1973-2009. Then we select the superior model in terms of prediction power criteria and forecast consumption until 2025. According to the results, the PSO algorithm is efficient and accurate in forecasting consumption; and consumption behavior of Iranians is consistent with Duesenberry theory. In addition, the simulations by exponential consumption model indicate increasing average propensity to consume until 2025.  

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Households need to have a smooth level of consumption in order to maximize their utility. Among the factors influencing consumption smoothing are: the existence of a perfect capital market, lack of liquidity constraints and access to financial resources, so that individuals are able to borrow and lend in order to prevent their income and consumption fluctuations. This paper attempts to investigate the excess sensitivity of household consumption with emphasis on liquidity constraints in Iran using panel data related to two recessionary periods of 2013-2015 and the pre-recessionary period of 2010-2012. The results show that the excess sensitivity of consumption to current income is significant. This finding rejects the permanent income hypothesis based on rational expectations in Iran. The asymmetric impacts of the positive and negative growth rates of income on consumption confirm the liquidity constraints of households. Identification of the socioeconomic characteristics of households with higher sensitivity, especially during the recession of 2013-2014, suggests that households without access to or inadequate access to bank loans, the elderly-headed households, families headed by non-governmental employees, low-income and rural households are more sensitive to income in comparison to the other households.