Linear Approximate Almost Ideal Demand System Research Articles

Indonesia’s Pulp Export Performance In the China Market: An Analysis Using Almost Ideal Demand System Approach

Indonesia is one of the world's leading pulp producers. Both domestic consumption and global demand are increasing annually. As Indonesia seeks to meet the escalating global demand for pulp raw materials, China is emerging as a major destination for its exports, which underscores the strategic importance of this market. This study aims to evaluate the comparative advantage of Indonesian pulp exports and to identify the price, cross-price and expenditure elasticities of pulp demand in the Chinese market. Using the Revealed Comparative Advantage (RCA) method and the Linear Approximation-Almost Ideal Demand System (LA/AIDS) model, this research analyzes annual time series data covering the period 2003-2022, focusing on the quantity and export value of chemical pulp (HS 470329). The results show that Indonesian pulp has a comparative advantage in the Chinese market, as indicated by Indonesia's RCA index greater than one. However, this comparative advantage is declining over time. At the same time, China's sustained increase in pulp consumption underscores the intensified competition among pulp-exporting countries for market share in China. Using the LA/AIDS model, the estimation results highlight a different dynamic in the Chinese pulp market: Japanese pulp emerges as a complementary product to Indonesian pulp, while Thailand and Brazilian pulp act as substitutes. These findings have valuable strategic implications for Indonesian policymakers and industry stakeholders in managing the complexities of global pulp trade dynamics

Food Demand Projection and Consumption Patterns of Urban Households in Nigeria’s Kano State

Changes in population and income are essential components for altering the pattern of food demand. In light of the importance of food demand analysis, this study set out to ascertain urban household consumption trends in Nigeria’s Kano State in order to forecast future demand levels for certain food items. This research contributes to becoming a basis for policymakers to increase food productivity. A household’s cross-sectional survey data elicited through a well-structured questionnaire complemented with an interview schedule from a total of 144 households chosen via a multi-stage sampling procedure was used for the study. The collected data were analyzed using both Linear Approximate/ Almost Ideal Demand System (LA/AIDS) and factor analysis models. Based on empirical evidence, households’ poor purchasing power is owed to high food inflation, which causes them to have low dietary diversity. Besides, the necessary and luxury goods, respectively, were rice, beans, spaghetti, and meat; and millet, yam, Irish potatoes, semovita, fish and groundnut. Meanwhile, maze, garri, and palm oil were established to be inferior commodities. Besides rice and semovita being everyday goods, they demand high price-sensitive commodities. Consequently, to maintain the status quo in the households’ welfare, the onus lies on policymakers to compensate consumers if there is a rise in the prices of local rice, indomie and groundnut oil. The study advises policymakers to increase the productivity of those food items projected to witness the steep-to-gentle rise in demand, and government should endeavour to adopt macro-economic policies with human-face so as to cushion/soften households’ economic hardship in the study area.

Examining Fruit Demand Elasticities In Pakistan

Abstract Research background Income and prices are important factors that determine and decide households consumption decisions and behavior. Purpose and research methodology This paper aims to examine fruits’ demand elasticities in Pakistan by using the Linear Approximate Almost Ideal Demand System (LA/AIDS). For this purpose, data from the Household Integrated Economic Survey (HIES) 2018–2019 part of Pakistan Living Standard and Measurement is used for the selected fruits. Results Marshallian, Hicksian, and expenditures elasticities were calculated through the estimated parameter from the Linear Approximate Almost Ideal demand system. The results show that all the estimated expenditure elasticities of the selected fruits for Pakistan are positive. The magnitude of expenditure elasticities for bananas, malta, apple, grapes, watermelon, plum, and almonds, is less than unity, and are thus categorized as normal food items. The estimated uncompensated own price demand elasticities for all fruits are less than unity (inelastic) for Pakistan and thus categorized as necessities. Based on the cross-price uncompensated demand elasticities eighteen fruits are reported as gross complements and three fruits are gross substitutes. Most of the fruits are categorized as neutral fruits having no cross-price effect on each other’s demand as their estimated elasticities are closer to zero. Only apples with grapes and almonds are found to be notable substitutes. As most of the price elasticities of fruits are inelastic, any change in their price would result in a massive increase in expenditure on these fruits. As a result, the government may adopt policies for the stabilization of fruit prices to meet the minimal daily food requirements of the lower segments of society. Novelty This study is an attempt to estimate demand elasticities for individual fruit as very little research is available in the study area for individual commodities.

A demand analysis with a dynamic approach to LA/AIDS for the Italian bottled water industry and its related non-alcoholic beverages

This paper analyses the demand for non-alcoholic beverages in Italy with Istat and Bevitalia data, including bottled water, soft drinks and juices, over the period of 2011–2020, using a dynamic approach based on the Linear Approximate-Almost Ideal Demand System (LA/AIDS). The analysis takes into account the correlation among the bottled water, soft drink, and juice industries, and the effects of changes in prices, income, and quantities on the demand for each type of beverage. Our findings suggest that, in Italy, during the considered period, the income elasticity of the three products was positive, indicating that they are normal goods, albeit bordering on the line between necessary and luxury goods. Bottled water and juices are classified as luxury goods, whereas soft drinks are more inclined to be classified as necessary goods. Additionally, soft drinks and bottled water are price-elastic goods, whereas juices and bottled water, or juices and soft drinks, are price-inelastic goods. Our results also indicate that bottled water is the most widely consumed good, followed by soft drinks and juices. Finally, we recommend policy interventions aimed at promoting healthier consumption habits, such as taxes on sweet drinks or subsidies for drinking water consumption. Overall, our findings provide new insights into the dynamics of demand for non-alcoholic beverages in Italy, which can inform policy decision-makers focused on promoting public health and welfare.

Households food consumption pattern in Pakistan: Evidence from recent household integrated economic survey

The analysis of food consumption pattern is a primary concern of any developing country because it is related with food security. Pakistan is one of the emerging nations of the developing world.Due to the similarities and differences in households' food consumption behavior, income distribution, the effects of alternative tax structures, cost-benefit analyses, and the choice of cost of living index, the study of households' food consumption pattern is crucial for a developing nation like Pakistan. Furthermore, for Pakistan's food security in the present and the future, an analysis of food consumption pattern is crucial. The main objective of this study is to analyze the households' food consumption pattern. Linear Approximation Almost Ideal Demand System (LA/AIDS) is applied using data from Household Integrated Economic Survey (HIES) for the year 2018–19. This study makes a significant contribution by estimating household age composition elasticities, which were absent from earlier studies. Results from the income elasticities reveal that milk, meat, and fruits are luxuries food items. Similarly, on the basis of inelastic income elasticities we declared cereals, pulses, vegetables, sugar, and ghee as necessity food items. Results from the compensated own price elasticities show that the eight food commodity groups have inelastic own-price elasticities. This implies that these food commodities are integral food items of household diet. Results from the compensated cross-price elasticities shows that cereals and pulses, cereals and vegetables, pulses and vegetables, milk and fruits, meat and fruits, and milk and ghee are gross substitutes. On the other hand, pulses and meat, pulses and fruits, and ghee and meat are gross complements. According to the findings of the household age composition elasticities, adding children to a household significantly increases its sugar consumption while significantly reducing its fruit consumption. Any increase in the size of the household by an adolescent, adult, or a person in their middle age results in a significant increase in the consumption of cereals and a significant drop in the consumption of fruits. Finally, any increase in the size of the households brought about by an elder resulted in a significant rise in the consumption of cereals and a significant drop in the consumption of vegetables.

Household Demand for Food Prepared at Home and Food Away from Home in Indonesia

This study aims to analyze the demand for food among Indonesian households, consisting of foods prepared at home (FPAH) and food away from home (FAFH). Utilizing longitudinal data from the National Socioeconomic Survey 2011-2013, combined with the Village Potential Statistics, the study estimates the demand with the Linear Approximated Almost Ideal Demand System (LA/AIDS). The results show that both FPAH and FAFH are normal goods but FAFH is more elastic than FPAH. Additionally, in terms of income elasticity, we found that households show stronger responses in consumption on FAFH, compared to FPAH. We also present heterogeneity analysis on different types of household characteristics.

Estimation and Analysis of Food Demand Patterns in North Kalimantan

North Kalimantan Province is in the top five provinces with Indonesia's highest percentage of food-insecure populations in 2018. Meanwhile, of the five provinces, only North Kalimantan Province has the status of a newly expanded province. As a province that is still relatively new, this is a challenge for the local government to ensure the availability of food for its people. Therefore, this research aims to analyze the factors that influence patterns and changes in food consumption due to prices, income, and socio-demographic characteristics of households in North Kalimantan Province. This study uses A Linear Approximated Almost Ideal Demand System (LA/AIDS) for 13 food commodity groups using Susenas data in 2018. The results show that the prices of each commodity group and other commodities significantly influence the proportion of food expenditure. In addition, the number of household members, household residences, and head of household education substantially affects the pattern of household food consumption. Price elasticity provides a positive value for 11 commodity groups, and only two commodities are negative, namely vegetables and fruits, while cross elasticity is quite varied. The policy implications that the government can carry out are to ensure food availability by using this research information to create work programs and strategic policies to ensure the fulfillment of food needs

Factors affecting household carbohydrate food consumption in Central Java: Before and during the COVID-19 pandemic

Abstract The COVID-19 pandemic has resulted in a change in food demand. In Central Java, during the pandemic (2021), the proportion of expenditure on the grain food group was higher than in 2020; meanwhile, the proportion of the ready-to-eat food group decreased. This study aims to analyze the pattern of food consumption of carbohydrate sources, the influencing factors, and the elasticity of consumption in households in Central Java before and during the COVID-19 pandemic. This study uses data from the National Socio-Economic Survey (Susenas) for 12 districts/cities in Central Java consisting of 9,812 in 2019 and 10,636 households samples in 2021. Data analysis used the Linear Approximation Almost Ideal Demand System (LA-AIDS) method. Results of the study show that the COVID-19 pandemic has caused changes in the household consumption pattern of carbohydrate-source food in Central Java. The proportion of expenditure on rice, wheat flour, shelled corn, cassava, and potatoes has increased. On the other hand, wet corn, instant noodles, and white rice decreased. The price of food sources of carbohydrates and the number of household members positively affect the consumption of food sources of carbohydrates. At the same time, income has a negative effect. There are differences in the effect of the location of the residence on the consumption of food sources of carbohydrates before and during the pandemic. The value of own-price elasticity and income elasticity shows that before the pandemic, rice was a staple good whose consumption was inelastic. Before and during the COVID-19 pandemic, wheat flour, wet-skinned corn, shelled corn, potatoes, white rice, and cassava in the pre-pandemic period was Giffen because the price elasticity was positive, and the income elasticity was negative. Meanwhile, rice during the pandemic, instant noodles before and during the pandemic, and cassava were Veblen goods because their price and income elasticity were positive. Cross elasticity shows that before the pandemic, most of the relationships between food sources of carbohydrates were substitutes, while during the pandemic, most of the relationships between food sources of carbohydrates were complementary.

Potential impact of food inflation on households’ welfare: Evidence from Pakistan

The global food price crises of 2007–2008 and the recent resurgence of food inflation have gained attention of the researchers about the causes and consequences of this volatility in food prices around the globe. This paper aims to examine the potential impact of food inflation on households’ welfare in Pakistan. For this purpose, the authors used a flexible Linear Approximate Almost Ideal demand System (LA/AIDS) to estimate the food demand pattern using the recently available Household Integrated Economic Survey of Pakistan for the year 2018–2019. Food products were categorized into thirteen food groups including milk, meat, fruits, vegetables, sugar, beverages, cereals, wheat, rice, oil & fats, tea, condiments and baked products. The estimated model was used to simulate different price increase scenarios in each of the currently own price. We found out that the estimated loss in the consumption was consistently high for milk, sugar, cereals, rice, wheat, meat and oil & fats. The issue of limited diversity in the dietary pattern and persistently food inflation will result in alarming food security in the country. The Effect of an increase in the general price level on food consumption could only be reduced by enhancing households’ purchasing power in the current scenario. The outcome of this research study will help policymakers in the agriculture sector to develop reliable and sound policy designs that will help control the implications of food inflation on household welfare loss.

The Effect of Trade Policy on The Position of Indonesian Coffee Market among The Major Importing Countries

Indonesia is the largest coffee producer in the world after Brazil, Vietnam and Colombia, but it was confronted with market problems. This paper, therefore, analysed the demand system as the position market for Indonesian coffee, either green bean or roasted coffee in the main importing countries such as Germany, Japan and The United States. The linear Approximate Almost Ideal Demand System (LA/AIDS) model was used to analyse the position of Indonesian coffee and its competitors. Time series data from 1996 to 2017 were obtained for the analysis. Empirical results indicated that most of the slope coefficients were statistically significant and in accordance with microeconomic theory. The variables of trade policy effected the Indonesian coffee trade. Indonesian green bean was found to be elastic in Germany, Japan, and The United States. Then, Indonesian roasted coffee was found to be inelastic in Japan. Indonesian green bean was a luxury good only in Germany, but Indonesian roasted coffee was an inferior good in Germany and The United States. Both Indonesian green bean and roasted coffee were a necessity in Japan. Almost Indonesian coffee substitute for Brazilian coffee and Colombian coffee, and complementary with Vietnamese coffee as its competitor.

A micro‐level data analysis of household energy demand in Khyber Pakhtunkhwa, Pakistan: An application of linear approximate almost ideal demand system

AbstractThis study examines energy choice, consumption pattern and household energy expenditure in Khyber Pakhtunkhwa (KPK) using the Linear Approximate Almost Ideal Demand System (LA‐AIDS). The study used micro‐level data to estimate the price and expenditure elasticities by employing (SUR) methodology. Empirical findings showed that energy choice, consumption patterns, and demand are different for urban‐rural households in the province. Each household living in KPK spent 1838.81 Rupees (9.92%) on energy purchases out of its total average monthly expenditure of Rs. 18,542.79. Compared to urban households, households living in rural areas spend more on energy consumption in a proportionate manner. The expenditure elasticities estimated for all energy sources are positive and statistically significant. Furthermore, the result showed that expenditure elasticities estimated for urban and rural households are less than one, suggesting that all the sources of energy are necessities. Natural gas and electricity are the main energy sources for urban households, while firewood and electricity are key energy sources for rural households in the province. The study suggested that rural households need to switch from conventional energy sources to modern and renewable energy sources, which would reduce the cost of energy use.

Estimating the Demand Elasticity of Rice in Bangladesh: An Application of the AIDS Model

This study determines the causes of consumption, compensated, and uncompensated demand for rice using the Linear Approximate Almost Ideal Demand System (LA-AIDS) model in Bangladesh. The model was used along with the corrected Stone Price Index. The study’s findings showed that the income elasticity of demand for rice was only 0.76, indicating that rice is a normal and necessary food item. The own-price elasticity (compensated and uncompensated) showed that all food items were price inelastic. The rice’s own-price elasticity demonstrated that if the price falls by 10%, rice demand will rise by 8.21%. This cross-price elasticity showed the weak substitution effects of a price change. Therefore, price interference may not lead to a substantial effect on food demand.

Food Security Assessment in Azad Jammu and Kashmir: Empirical Analysis of Dietary Diversity, Current and Project Food Demand and Supply-Demand Gap

This study attempts to determine the dietary diversity score for different food groups and estimates the current demand for different food groups in AJK. Data for this study was collected from 1250 households covering all 10 administrative districts of AJK by following multi-stage sampling techniques through a comprehensive interview schedule. Ten commodity groups (Wheat, Rice, Milk, Meat, Vegetables, Fruits, Pulses, Oil/Ghee, Tea and Other food were developed for analysis. Linear Approximate-Almost Ideal Demand System (LA-AIDS) model was used for estimating food demand elasticities through Zellner’s Seemingly Unrelated Regression by using STATA software. All the 10 food groups were found normal goods, except milk and fruits (income elasticity higher than unity). This implies that in future demand for milk and fruits would increase more proportionately as income would increase. The own price elasticities of all 10-food groups were also found congruent to economic theory (Wheat-0.28, Rice-0.65, Milk-0.92, Meat-0.34, Fruits-0.61, Vegetables-0.21, Pulses-0.29, Oil and ghee-0.04, Tea-0.35 and Other food-0.32). The income and own price elasticities depicted that wheat, vegetables, pulses and oil and ghee are necessities as compared to other food groups. The cross-price elasticity illustrated that rice could be a substitute for wheat and wheat for rice in the State of AJK. The Berry’s Index (82.43) depicted that food was diverse on average with a minimum Index value of 61.31. The study of different factors in relation to Berry’s Index depicted that education and income significantly and positively affect Berry’s Index while location of household in urban or rural area do not affect diversification of food. Inclusion of all necessities in Food Stamp program and Ramadan package and efforts by agriculture and livestock department regarding improved production of food commodities are recommended.

Domestic Consumption Pattern of Cereal Commodities in Nigeria

The present research empirically study the demand pattern of cereal commodities for domestic use in Nigeria using time series data which spanned from 1966 to 2018. The data covered the domestic quantities and price series of the five most important domestically used cereal commodities. The sources of the data were FAO and USDA databases and the collected data were analyzed using descriptive statistics and linear approximate almost ideal demand system (LA/AIDS). The empirical evidence showed that all the considered goods were normal goods and mostly a necessity except for wheat which is a luxury. In addition, domestic consumption of these commodities was sensitive to changes in their respective prices. With wheat been a luxury commodity, it can be inferred that an increase in per capita income would tend to bring about a paradigm shift from the consumption of staple foods to non-staple food (wheat). This indicates that households tend to diversify their diet composition. Also, it was observed that most of the good pairs are complementary (uncompensated cross-price elasticity) while on the other hand (compensated cross-price elasticity), most of the good pairs are substitutes. The empirical evidence showed the income effect which owes to price changes for all the selected commodities to be moderate. Therefore, onus lies on the policymakers to embark on mass production of wheat in order to free the country from wheat food insecurity bondage caused by external influence, an impediment to the barometer that strikes a balance between the forces of demand and supply.

ANALYSIS OF FOOD CONSUMPTION PREFERENCES AND FOOD DEMAND IN CENTRAL JAVA, INDONESIA

The efforts of the Government in food diversification of rice to local food thus generating household conditions that tend to switch to wheat consumption compared to local commodities. So the necessary analyse to look at preferences in consuming the food commodities. Besides seeing the influence of price changes and the expenditure against the demand for food as the evaluation of food diversification successfully implemented. This analysis were using Susenas data (2016) analyzed by the Linear Approximation/Almost Ideal Demand System (LA/AIDS) model. The results of the analysis note that the highest preference is present on rice and flour, seen from the amount of consumption as well as the proportion of its expenditure. The results of the demand elasticity indicates that diversifies effort still hadn't done very well because there were still a dependency of the rice. So that the effort to maintain the affordability of the rice should still be enacted.

Modelling the Demand of Fresh Meat by Households in Malaysia

There have been some changes in Malaysians’ food preference as Malaysia is one of the most developing countries in Asia. These changes in consumption pattern have some impact on the agriculturally based food industry. One of the changes is in the preference for fresh meat such as poultry, beef, mutton, and other meat. This study is focusing on demand elasticity of fresh meat by households in Malaysia. This study has obtained demand elasticity of fresh meat via Linear Approximate Almost Ideal Demand System (LA-AIDS). Data from the Household Expenditure Survey (HES) 2014 has been used to build a statistical model in estimating the demand elasticity. Keywords: demand elasticity; Linear Approximate Almost Ideal Demand (LA-AIDS); Household Expenditure Survey (HES) 2014

Towards agricultural demand for the main energy carriers in Iran: Application of linear approximate almost ideal demand system (LA-AIDS) analysis

Abstract Due to the necessity of cognizance of demand for the various forms of energy in the agricultural sector in Iran’s economy and considering the effects of price liberalization policies on forms of energy, analysis of the main energy carriers’ demand is very important. This study used the LA-AIDS approach and ISUR technique to estimate the demand and elasticities for various energy carriers. Also, the welfare effects of increasing energy prices under the 20, 40, 60, 80 and 100% scenarios are evaluated using the compensating variation (CV). The uncompensated and compensated own-price demand elasticities for oil products, electricity and, natural gas carriers were −1.21, −0.85 and −0.55, and −0.98, −0.32 and −0.30, respectively, confirming the demand theory. The cross-price elasticities showed that electricity has substitutability and complementarity relationship with oil products and natural gas, respectively, while the relationship between natural gas and oil products is a substitutability relationship. The income elasticities of energy usages estimated to be 0.64, 1.2 and 1.05. Agricultural producers’ welfare would experience a further decrease in oil products and electricity price liberalization, though the welfare impacts of natural gas are trivial. As price elasticity is different in the agricultural sector, price policies, then price liberalization and omitting energy subsidy should be applied based on the elastic or inelastic of energy carriers. The price policies effectiveness on oil products is more than electricity and natural gas. Given the prevalence of consumption and high price elasticities of oil products and pollutants, rising oil prices can reduce their consumption and environmental pollution.

ANALISIS PERMINTAAN PANGAN RUMAH TANGGA PENERIMA MANFAAT BANTUAN PANGAN NON TUNAI (BPNT) DI KOTA BOGOR

Food is a basic need and access to food is a human rights that must be fulfilled. Meeting food needs is the main target of food policy carried out by the government, especially for the poor household. One of the government's policies in terms of food is Non-Cash Food Assistance (BPNT). The purpose of this study was to analysis the food demand for BPNT's beneficiary household and not receiving BPNT. This study used primary data on food consumption with the highest share of expenditure of poor households in Bogor City. Demand for food was estimated by LA-AIDS (Linear Approximation Almost Ideal Demand System) model. The results this study showed that there were significant differences in the average consumption of rice, non-rice and animal protein consumption between BPNT and non-BPNT households. The highest of food expenditure in both households was processed food and beverages. The BPNT dummy variable did not sign for a share of food expenditure. The result of the estimate also showed that rice, animal protein, vegetables, food and beverages and cigarettes are inelastic at their prices elasticity. All types of food studied were normal goods. Non-rice, vegetables and processed food and beverages were substitutes for rice in BPNT recipient households while in non-BPNT only processed food and beverages was substitutes for rice. The interesting thing in this research was that cigarettes become a complimentary item to all foods.

KAJIAN SISTEM PERMINTAAN KOMODITAS SUMBER PROTEIN DI ENAM PROVINSI INDONESIA

The government's commitment to realize national food security through overcome food insecurity and malnutrition as the main program of the Ministry of Agriculture. This study aims to analyze differences in consumption of protein commodities based on two provincial categories and the effect of changes in prices and income on demand of protein commodities. The two provincial catagories are provinces which has protein consumption below Adequacy Rate of Protein (AKP), namely Jambi, Nusa Tenggara Timur, Maluku and provinces which has protein consumption above AKP, namely Jakarta, Jawa Barat, Jawa Timur. This study used the National Socio-Economic Survey (SUSENAS) in March analyzed by using Linear Approximate-Almost Ideal Demand System (LA/AIDS). The results showed that consumption of fish and meat in provinces above AKP is higher then percapita consumption in provinces below AKP, while the others percapita consumption like poultry, egg, tempeh, and tofu is higher in provinces above AKP. Price and expenditure elasticity is more elastic in provinces above AKP then price and expenditure elasticity in provinces below AKP. Generally, the commodity's own price elasticity is inelastic in both categories of provinces except eggs. The value of egg elasticity is greater than 1 (elastic), either in provinces above AKP or in the provinces below AKP. Based on expenditure elasticity, all commodities are normal goods. Fish, poultry, and eggs are luxury goods in the province above the AKP, while only fish and eggs are luxury goods in the provinces below the AKP.

Do Households Diversify Energy Sources or Switch to New Sources in Ethiopia? A Case Study in Wolkite Town

This study analyses weather households diversify their energy sources or switch to new sources. The study utilized cross-sectional data gathered from a randomly selected sample of 260 households in Wolkite town. The study employed linear approximation almost ideal demand system (LAAIDS).The model was constrained to comply with neoclassical theoretical restrictions on demand, and was estimated using Iterative Seemingly Unrelated Regression (ISUR).We found that households did not completely switch to new energy sources as suggested by the energy ladder hypothesis. Instead, they diversified their energy consumption through a process of fuel stacking (energy mix). We also found that the demand for energy was expenditure elastic, with the estimates of cross-price elasticity of the demand for energy sources attesting to the existence of energy substitution and complementarity in the study area. Furthermore, we document that prices of all energy sources (except kerosene), household total energy expenditure, sex (if male), age, years of education, family size, and residence type as main determinants of expenditure share of energy sources. Given the negative health and environmental consequences associated with massive consumption of fuel-wood and charcoal, the study suggests that making modern energy source easily accessible, incorporating environmental costs attributable to consumption of fuel-wood and charcoal in the energy planning process, and imposing environmental tax equivalent to the costs to help enhance transition (switch) to modern energy sources as solution to improve the situation. Keywords : Almost Ideal Demand System, Household energy demand, Energy complementarity, Energy mix, Energy switch, Ethiopia DOI : 10.7176/JETP/9-1-03