eyd Ekonomik Yaklaşım Derneği / Association Ekonomik Yaklaşım 2015, 26(97): 1-22 www.ekonomikyaklasim.org doi: 10.5455/ey.35714 The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey A. Ali KOÇ 1 Gülden BÖLÜK 2 Fatma Banu BEYAZ SİPAHİ 3 04 Şubat 2015’de alındı; 09 Temmuz 2014’de kabul edildi. 22 Ekim 2015’den beri erişime açıktır. Received 04 February 2015; accepted 09 July 2015. Available online since 22 October 2015. Araştırma Makalesi/Original Article Abstract This study analyzes the welfare impact of the residential electricity tariff escalation initiated in July 2008 on households in Turkey. Empirical analysis consists of estimation of household electricity demand using TurkStat “2007, 2008 and 2009 budget survey" data and Hicksian compensating variation of welfare. The estimated income elasticities by income strata were found to be close to each other, confirming that electricity is a necessity good and the magnitude of the elasticities decreases as income goes up (ranging from 0.74 to 0.91 for income strata). The magnitude of the income elasticities by income strata was found to be very low compared to the long-run income elasticities in previous time series studies. The estimated income elasticity by income strata and the mean value of the Marshallian long-run own-price elasticity for residential electricity obtained from previous time series models were used to obtain Hicksian own-price elasticities using Slutsky decomposition for each income strata. The welfare measure which relied on Hicksian compensating variation indicated that welfare loss of households from 2007 to 2009 was around 9-10 percent by income strata as compared to the situation before tariff adjustment. It is expected that welfare losses would be greater if the analysis period were extended to 2012. Keywords: Residential electricity demand, income elasticity of electricity demand, welfare impact of electricity price escalation, Slutsky decomposition. JEL Classification: D12, D13, D60. © 2015 Published by EYD 1 Yazışmadan sorumlu yazar (Corresponding author).Akdeniz University, Department of Economics, Antalya, Turkey. E-mail: alikoc@akdeniz.edu.tr 2 Akdeniz University, Department of Economics, Antalya, Turkey. E-mail: guldenboluk@akdeniz.edu.tr 3 Akdeniz University, Department of Economics, Antalya, Turkey. E-mail: banubeyaz@gmail.com Ekonomik Yaklaşım ISSN 1300-1868 print © 2015 Ekonomik Yaklaşım Derneği / Association - Ankara Her hakkı saklıdır © All rights reserved A. Ali KOÇ, Gülden BÖLÜK, Fatma Banu BEYAZ SİPAHİ 2 Özet Türkiye’de Tarife Düzenlemesi ve Ekonomik Krizin Hanehalkı Elektrik Talebi Üzerine Etkisi Bu çalışma, Türkiye’de Temmuz 2008 yılında tırmanmaya başlayan konut elektrik tarifesinin hanehalkının refahı üzerindeki etkisini analiz etmektedir. Ampirik analiz, TÜİK “2007, 2008 ve 2009 bütçe anket” verilerini kullanılarak hanehalkı elektrik talebinin ve Hicksgil telafi edici refah değişiminin tahmininden oluşmaktadır. Gelir gruplarına göre hesaplanan gelir esnekliklerinin birbirlerine yakın bulunması elektriğin zorunlu bir mal olduğunu ve gelir artarken (gelir grupları için 0.74-0.91 arası değişen) esneklik büyüklüğünün azaldığını doğrulamaktadır. Gelir gruplarına göre hesaplanan gelir esnekliklerinin büyüklüğü, daha önceki zaman serisi çalışmalarında hesaplanan uzun dönem gelir esnekliklerinden çok daha düşük bulunmuştur. Gelir gruplarına göre hesaplanan gelir esneklikleri, önceki zaman serisi çalışmalarından elde edilen elektriğin Marshallian uzun dönem fiyat esnekliği ve her bir gelir grubu için Slutsky ayrıştırması kullanılarak Hicksian fiyat esneklikleri elde edilmiştir. Hicksgil telafi edici refah değişimine göre, tarife düzenlemesinden önceki durumla karşılaştırıldığında gelir gruplarına göre 2007-2009 döneminde hanehalkının refahı % 9-10 civarında azalmıştır. Eğer analiz dönemi 2012 yılına uzatılırsa, refah kayıpları çok daha yüksek oranlara ulaşırdı. Anahtar Kelimeler: Hanehalkı elektrik talebi, elektrik talebinin gelir esnekliği, elektrik fiyat artışının refah etkisi, Slutsky ayrıştırması. JEL Sınıflaması: D12, D13, D60. © 2015 EYD tarafından yayımlanmıştır Bu makalenin adını ve doi numarasını içeren aşağıdaki metni kolayca kopyalamak için soldaki QR kodunu taratınız. Scan the QR code to the left to quickly copy the following text containing the title and doi number of this article. The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey http://dx.doi.org/10.5455/ey.35714 1. Introduction The demand for electricity has increased due to the remarkable economic growth, rapid urbanization, and relatively high population increase in Turkey over the last years. Electricity production increased from 8,623 Gwh to 229,395.1 Gwh between 1970 and 2011. Gross demand of electricity in Turkey reached 230,306 Gwh in 2011, with an average annual growth rate of around 10 % in the last decade (TEIAS, 2012). Electricity market restructuring process which was initiated in 2001 aimed to meet the rapidly increasing demand for electricity in the country. The process was affected and accelerated by three main factors: (1) a financial stabilization program which has been implemented under the supervision of the World Bank and International Monetary Fund (IMF), (2) harmonization of the market with the European Union, and (3) attracting private investments to the energy sector to meet the The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey 3 increasing electricity demand (Atiyas and Dutz, 2004). The restructuring process also envisaged that electricity tariffs should be cost-based, and cross subsidies across segments (residential, industry) and regions (East and West) should be removed (Bagdadioglu, 2007). The retail price of electricity regulated by the government was constant in nominal terms (declined in real terms) between 2003 and 2007 and has escalated since July 2008. However, electricity tariff (in nominal terms) was adjusted in several steps and as a result, the nominal price increased 59 percent from July 2008 to February 2013, even though the deflated price still did not exceed the price range observed from January 2003 to February 2013 (Figure 1). The state regulated retail price can be regarded as third degree price discrimination since residential users pay a higher tariff than industrial/service users. Figure 1: Monthly Residential Electricity Tariffs in Turkey (2003:01-2013:01) Real Price (Kwh/TL) Nominal Tariff (Kwh/TL) Source: TurkStat, 2013. The effect of electricity tariff changes on households’ consumption and welfare is a very important for policy decisions. As of 2011, there were 32.6 million residential users of electricity in Turkey. Approximately 24 percent of aggregate electricity was consumed by residential users in the country (TEDAS, 2012; TurkStat, 2011). Although electricity market has been very dynamic in Turkey in recent years, academic studies analyzing the impact of various economic factors on residential demand is limited, and the existing studies have 4 A. Ali KOÇ, Gülden BÖLÜK, Fatma Banu BEYAZ SİPAHİ focused solely on price escalation. However, Bagdadioglu, Basaran, and Waddams Price (2007) analyzed the impact of electricity price changes on consumer welfare using the “2003 household budget survey" data conducted by TurkStat. In this study, the authors employed an own-price elasticity of electricity demand of -0.23, which was borrowed from studies conducted in other countries. Furthermore, the own-price elasticity was assumed to be the same for different consumer segments in terms of income quintile, and the welfare measurement was based on an ordinary Marshallian demand curve 4 . Akkemik (2009), examined the liberalization of Turkish electricity market reform using computable general equilibrium (CGE) model. The author found that market reform would enhance the efficiency in electricity production and improve consumer's welfare because of the lower electricity prices. Zhang (2011) estimated a short-run residential electricity demand function to evaluate the distributional consequences of the tariff escalation using a national sample of 18,671 Turkish households from the “2008 and 2009 Household Budget Survey” of TurkStat. In this study, the author estimated own-price and expenditure elasticities based on income strata using an electricity demand model specified in double-log functional form including sociodemographic variables. The welfare changes of households by income strata were evaluated with the own-price elasticities obtained by the demand model based on an almost constant price variable from 2008 to 2009 (See Figure 1). During the data analysis period, however, nominal electricity tariffs escalated only four times. Moreover, while price tariffs showed even less variation in real terms between January 2008 and December 2009, it was almost stable after October 2008 to December 2009. Therefore, price elasticity with non-variable real price is questionable from the viewpoint of the assumption of OLS estimator. The author found, however, electricity is inferior good among Turkish household which is not reasonable at the economic viewpoint for a developing country and is not comparable with literature. In addition to the less reliable price and income elasticity, the effect of economic crisis on household expenditures was not taken into account to evaluate the impacts of price escalation in a study conducted by Zhang (2011). Furthermore, both price and expenditure variables were not deflated although there was an increase of almost 16 percent in consumer prices during the period considered. Electricity price in real terms however increased 33 percent if longer time period is considered such as January 2007 and December 2009 (See Figure 1). 4 It has been proved that the Marshallian demand curve was not suitable for estimating the welfare changes (Huang, 1993, pp.217-218; Deaton and Muellbauer, 1980, pp.185-186). The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey 5 The main aim of this study is to evaluate the welfare effects of household electricity price escalation by income strata in Turkey. For this purpose, the study estimates “a residential electricity demand model” using the “2007, 2008 and 2009 Household Budget Survey of TurkStat” in order to obtain expenditure elasticity by household income strata in Turkey. The parameters obtained from different years enable us to verify whether household electricity consumption differs during the economic cycles as well as expenditure (income) elasticities. This study incorporated the mean value of own-price elasticity compiled from various robust econometric studies for Turkey with time series data through the Slutsky equation, with the expenditure elasticities estimated using the 2007, 2008 and 2009 household budget data by income strata in order to obtain Hicksian compensating elasticities. Finally, the impact of the residential electricity price escalation on households in different income strata was measured by Hicksian price elasticity of demand instead of Marshallian elasticity. The welfare impact of price escalation on various segments of households by income strata was calculated by Hicks compensating variation method (Just, Hueth and Schmitz, 2004). The remainder of this paper is organized as follows. Section 2 provides the literature review for both the effects of price changes on consumer welfare and residential electricity demand studies. Section 3 introduces the methodology of the study. Section 4 describes the data set and descriptive statistics. Section 5 provides the results of the analysis and finally, Section 6 summarizes the results. 2. Literature Review There is an extensive body of literature examining residential electricity demand both in developed and developing countries. Energy demand studies were primarily initiated by Houthakker’s pioneering work (Houthakker, 1951). The literature on residential demand for electricity can be grouped into two main categories: The first group of studies focuses on traditional demand analysis, assumes homogeneous price elasticities and includes the income, price and household characteristics. Halvorsen (1975) analyzed residential electricity demand in America for the period of 1960-1970 using the 2SLS method. In this study, the real price of electricity, average real income per capita, heating degree days, average temperature, percentage of housing units and real price of households were used as explanatory variables in the demand model. The price and income elasticities were estimated for each year. Accordingly, the direct income elasticity ranged from 0.47 to 0.54, and price elasticity ranged 6 A. Ali KOÇ, Gülden BÖLÜK, Fatma Banu BEYAZ SİPAHİ from -1.0 to -1.21. Some studies in this group are based on the household production theory and use micro models. In these studies, residential electricity demand is a conditional demand derived from the demand for housing needs such as cooking food, hot water, washing, and so on. Based on this theory, household purchases are input factors in order to produce the final goods which appear in the households’ utility function (Shi, Zheng and Song, 2012). Hsiao and Mountain (1985) estimated short-run conditional demand for electricity using the 1980 energy application survey for Ontario, Canada. In this study, electricity demand was assumed to be derived demand of the services supplied by the stocks of electricity using appliances and the short-run income elasticity was estimated to be 0.17. Barnes, Gillingham and Hugemann (1981) analyzed the residential electricity demand as a function of income, price, appliancespecific factors and demographic variables, heating and cooling categories. The short-run demand parameters were estimated using household data from the 1972-73 Consumer Expenditure Survey covering 10,000 individuals in the USA. The price and income elasticities of residential electricity were found to be -0.550 and 0.20, respectively. Yoo, Lee and Kwak (2007) employed the bivariate model to estimate the residential electricity demand for Seoul using the household survey in 2005. The study showed that income, size of family, ownership of a plasma TV and air conditioning unit positively affected residential electricity demand. The price and income elasticities were calculated to be -0.25 and 0.06, respectively. Filippini and Pachauri (2002) analyzed the residential electricity demand using 1993-1994 disaggregate survey data for the urban areas of India. Electricity demand was assumed to be a function of the price of electricity and kerosene, stock appliances, income, geographic and demographic variables such as the number of household members and the size of houses. The elasticities were differentiated by seasons. Price elasticities were estimated to be -0.32 for winter, -0.16 for summer and -0.39 for the monsoon months. Income elasticities were estimated to be 0.68, 0.66 and 0.65 for the same seasons. Moreover, it was found that regional differences and the house size had positive effects on electricity demand, and LPG was a substitute for electricity during the summer time. Petersen (1982) tried to identify the differences between rural and urban usage of household electricity for Utah using a dataset consisting of 2.155 customers in 1980. The study concluded that rural residents used significantly more electricity in the winter time, and the differences between rural and urban electricity usage were primarily due to differences in the stock of devices using electricity. Moreover, the income elasticity of electricity was The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey 7 estimated to be 0.005. Parti and Parti (1980) analyzed residential electricity demand using cross-section data consisting of 5.286 individuals for San Diego in a conditional demand framework. It was assumed that the total energy consumed by a household is the sum of the energy used for household appliances. The price and income elasticities were estimated to be -0.58 and 0.15, respectively. Tuzun (2002) estimated the residential electricity demand as a function of electricity price, prices of substitutes, income level, weather (HDD and CDD), population, and housing stock. Demand was estimated by 2SLS using pooled data for the period of 1980-2000 in California. The elasticity of price and income was estimated to be 0.23 and 0.013, respectively. Reiss and White (2005) analyzed residential electricity demand for California using the 1993 and 1997 household survey. The authors estimated the mean price elasticity of electricity and income elasticity for space heating by households for all income quintile to be-0.39 and 0.0, respectively. The second group of residential electricity demand studies uses the advantages of a great variety of time series and pooling techniques. These studies usually use the popular error-correction models (ECM), cointegration methods, analyze the short-run and long-run behavior of electricity and effects of shocks on demand. Furthermore, Holtedahl and Joutz (2004) examined residential electricity demand in Taiwan using a dataset that covered the 1958-1995 periods. Short-run and long-run elasticities were differentiated using the ECM. The estimated short-run and long-run elasticities were 0.23 and 1.04 for income and 1.63 and 3.91 for urbanization. The own price elasticity was estimated to be -0.15. Hondroyiannis (2004) modeled residential electricity demand using the VECM estimation model and the study employed monthly data for the 1986-1999 period. Long-run residential electricity demand was estimated to be a function of real income, real price and weighted average temperature. The estimated long-run elasticities of the income, price and temperature in this study were 1.56, -0.41 and -0.19, respectively. Narayan and Smyth (2005) estimated the long and the short-run elasticities of residential electricity demand in Australia using annual time series data for the 1969-2000 periods. Income elasticity was estimated to be 0.0121 for the short run, and 0.0415 for the long run. Price elasticity was calculated to be -0.263 and -0.541, respectively. Moreover, it was found that temperature has a positive effect on energy consumption and is significant in the long run. Narayan, Smyth and Pasarad (2007) estimated the long-run and short-run income and price elasticities of residential electricity demand in 67 countries using panel A. Ali KOÇ, Gülden BÖLÜK, Fatma Banu BEYAZ SİPAHİ 8 cointegration techniques. The study used annual data series for the 1978-2003 periods and natural gas price was additionally included into the model as a substitute for energy price. Short-run elasticity of residential electricity was computed to be -0.10. While the long-run income and price elasticities of electricity were calculated to be 0.31, and -1.45, the price elasticity of natural gas was calculated to be 1.77. Narayan (2007) analyzed the residential electricity demand of G7 countries using annual data for the 1978-2003 periods using the cointegration method. He found that the USA has the smallest elasticity among the G7 countries. Albertini and Filippini (2010) empirically analyzed residential electricity demand using the annual aggregate data of 48 states for the 1995-2007 periods, and dynamic panel data analysis. The estimated elasticities for price, income, price of natural gas, household size, heating degree day and cooling degree day were -0.21, 0.28, 0.05, -0.74, 0.14 and 0.08, respectively. Halicioglu (2007) investigated the income and price elasticities of residential electricity demand by cointegration method and Granger causality test, using the annual series of the 1968-2005 periods for Turkey. Short-run income, price and urbanization elasticities of electricity were estimated to be 0.40, -0.46 and 0.67, respectively. Moreover, long-run income, price and urbanization elasticities of electricity were estimated to be 0.54, -0.63 and 0.02, respectively. Dilaver (2009) empirically analyzed income and price elasticities of residential electricity demand by structural time series modeling using annual data for the period of 1971-2006 in Turkey. Short- run income and price elasticities of electricity were estimated to be 0.41 and -0.10. Long-run income and price elasticities of electricity were estimated to be 2.21 and -0.57. Furthermore, Dilaver and Hunt (2011) revised their residential electricity demand model using longer and updated annual series (1960-2008) for Turkey. Short-run income and price elasticities of electricity were found to be 0.38 and -0.09. Longrun income and price elasticities of electricity were estimated to be 1.57 and -0.38. Nakajima and Hamori (2010) estimated the elasticities of residential electricity for 48 states in the USA using quarterly data for the period of 1993-2008 and panel cointegration techniques. Electricity demand was modeled as a function of price, income, cooling and heating degree day (CDD, HDD). Estimated elasticities were differentiated for the periods before and after the deregulation process. Elasticities of income, price, HDD and CDD after deregulation were calculated to be 0.85, -0.14, 0.17 and 0.64, respectively. Elasticities before deregulation were 0.38, -0.33, 0.19 and 0.56, respectively. The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey 9 Dergiades and Tsoulfidis (2011) examined the long-run and the short-run residential demand for electricity in Greece using ARDL cointegration method over the period of 1964 to 2006. Short-run income and price elasticities of electricity were estimated to be 0.64 and 0.092 for Greece. Long-run income and price elasticities of electricity were estimated to be 1.79 and -0.61. Table 1 provides the results of some selected residential electricity demand studies. Additionally, an extensive literature review on residential energy demand was further reported by Taylor (1975), Dahl (1993) and Madlener (1996). Blazquez, Boogen and Filippini (2012) analyzed residential demand for electricity using aggregate panel data for 47 provinces for the period from 2000 to 2008 in Spain. They estimated the short and the long run own price elasticities lower than unity. Moreover, authors found that weather variables have a significant impact on electricity demand. Fell, Li and Paul (2010) estimated residential electricity demand using household electricity expenditure data based on Consumer Expenditure Survey (7,500 households) in USA. Authors found that price and income elasticities ranges between -0.82 to -1.02 and 0.061 to 0.072, respectively. Table 1:Empirical Results of Selected Residential Electricity Demand Studies Source Country Study Period Income Elasticity Price Elasticity Halvorsen (1975) USA 1961-1969 0.54 (-1) to (-1.21) Parti and Parti (1980) San Diego 1975 0.15 -0.58 Barnes et al. (1981) USA 1972-73 0.20 -0.55 Dergiades and Tsoulfidis (2011) Greece 1964-2006 0.64-0.79 -0.092 to -0.61 Tuzun (2002) California 1980-2000 0.0125 -0.23 Filippini and Pachauri (2002) India 1993-1994 0.64 -0.29 to -0.51 Holtedahl and Joutz, (2004) Taiwan 1958-1995 1.57 -0.15 Hondroyiannis (2004) Greece 1986-1999 1.56 -0.41 Narayan and Smith(2005) Australia 1969-2000 0.04 -0.263 to -0.541 Reiss and White (2005) California 1993-1997 0.01 -0.39 Narayan et al.(2007) 67 countries 1978-2003 0.31 -0.10 to -1.45 Halıcioglu (2007) Turkey 1968-2005 0.70 -0.52 Dilaver (2009) Turkey 1971-2006 0.41 to 2.21 -0.10 to -0.57 Dilaver and Hunt (2011) Turkey 1960-2008 0.38 to 1.57 -0.09 to -0.38 Yoo et al.(2007) Seoul 2005 0.10 -2.245 Nakajima and Hamori (2010) USA 1993-2008 0.38 to 0.85 -0.14 to -0.33 Blazquez et.al.(2012) Spain 2000-2008 0.14-0.30 -0.11 to -0.24 Fell et.al.((2010) USA 2004-2006 0.061 to 0.072 -0.82 to -1.12 Source: Compiled by the authors. A. Ali KOÇ, Gülden BÖLÜK, Fatma Banu BEYAZ SİPAHİ 10 3. Measuring Welfare Impact of Price Change Reform efforts to restructure electricity markets have raised interest in assessing the consumer response to price changes. Knowledge of price and income elasticities is very useful and important in setting up pricing and energy policy (Hasio and Mountain, 1985). Consumers’ response to energy price change is additionally a very important issue due to its impact on consumer and social welfare (Freund and Wallich, 1997). Energy price increases have direct and indirect effects 5 on household energy usage. Household energy demand may be directly affected by energy price changes through complementary mechanisms. Higher energy prices will reduce discretionary income as households have less money to spend after paying their energy bill. In the case of less elastic demand for energy, this discretionary income would be larger. Increasing energy prices may create uncertainty about the future path of the price of energy and leads consumers to postpone irreversible purchases of consumer durables. Even these purchase decisions are reversible, as consumption can fall due to energy price shocks as households increase their precautionary savings. Moreover, household consumption of durables (operates with energy) will decrease, since consumers postpone the purchase of energy durables (operating cost effect) (Kilian, 2008). Indirectly, higher energy prices will cause reallocation of production inputs such as labor and capital away from energy intensive industries, as households tend to move towards more energy efficient durables (Zhang, 2011) 6. This study relies on Hicksian compensating variation measure (CV) in order to analyze the consumer welfare effects of electricity tariff changes. The correct measure of welfare is an integral of Hicksian demand curve rather than the Marshallian demand curve (Varian, 2004, pp.168). However, the use of the Marshallian concept as an analytical tool for measuring consumers’ surplus leads to errors and confusion. Taking the area under a compensated or Hicksian demand curve over a price change would be a more appropriate welfare measure, as Hicksian demand functions are the derivatives of the cost function, and the integration of demand functions provides the differences in the costs of reaching the same indifference curve at different price vectors (Huang, 1993, pp.217-218; Deaton and Muellbauer, 1980, pp.185-186). If welfare changes are analyzed for a normal good, the 5 Energy price increases also have macro-economic impacts (Kilian, 2008) but this study only concentrates on the direct effects of electricity prices on households. 6 Kilian (2008) for detailed information about direct and indirect effects of energy price shocks on consumers and economy. The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey 11 derivative of the Hicksian demand curve will be larger than the derivative of the Marshallian demand curve. Let's consider a situation where only the price of electricity moves from p0 to pı, income fixed at m=m0=mı and an expenditure function, E(p, u), defined as the minimum amount of expenditure necessary to get to a given level of utility u and a vector of electricity prices p. Supposing that consumer achieves utility u0, CV is given by (Huang and Huang, 2009); 𝐶𝑉 = 𝐸(𝑝1 , 𝑢0 ) − 𝐸(𝑝0 , 𝑢0 ) (1) where, the expenditure functions 𝐸(𝑝1 , 𝑢0 ) and 𝐸(𝑝0 , 𝑢0 ) are the minimum expenditure necessary to maintain the level of utility (𝑢0 ) given prices 𝑝1 and 𝑝0 . A positive CV implies a requirement for more spending to obtain the same utility level as before tariff changes, and thus there is a decrease in consumer welfare. By contrast, a negative CV implies a decline in spending, and thus a gain in consumer welfare. Let 𝑞 ℎ (𝑝1 , 𝑢0 ) be a vector of Hicksian compensated demand, a given price vector 𝑝1 and at the same initial utility level 𝑢0 . The CV can be expressed as the following implicit products of price and quantity vectors: 𝐶𝑉 = 𝑝1 ●𝑞ℎ (𝑝1 , 𝑢0 ) − 𝑝0 ●𝑞 0 (2) By further defining the 𝑑𝑝 = 𝑝1 − 𝑝0 as a vector of tariff changes, and 𝑑𝑞 ℎ = 𝑞 ℎ (𝑝1 , 𝑢0 ) − 𝑞 0 as a vector of compensated quantity changes, the CV equation can be transformed into 𝑑𝑝 𝑝0 𝐶𝑉 = (𝑝0 𝑞 0 )●( + 𝑑𝑞ℎ 𝑞0 + 𝑑𝑝 𝑑𝑞ℎ ● 𝑞0 ) 𝑝0 (3) Then the change in compensated demand can be approximated as 𝑑𝑞 ℎ = 𝑞 ℎ (𝑝1 , 𝑢0 ) − 𝑞 0 by applying the first-order differential form as follows; 𝑑𝑞ℎ 𝑞𝑖 ∗ 𝑑𝑝𝑗� = ∑ 𝑒𝑖𝑗 ( 𝑝𝑗 ) 𝜕𝑞ℎ 𝑝 (4) Where 𝑒𝑖𝑗 = ( 𝜕𝑝𝑖 )( 𝑞𝑗) is a compensated price elasticity of ith commodity with respect 𝑗 𝑖 to a price change in the j commodity. Moreover, 𝑑𝑞𝑖ℎ is a change in Hicksian demand for ith th good, such as electricity demand (Huang and Huang, 2009). Given the initial prices of electricity, a change in compensated quantities demanded could be calculated based on the information given on the compensated price elasticities and the price changes. The compensated price elasticities can be computed using the following Slutsky identity which decomposes the income and substitution effects of price changes (Huang, 1993). A. Ali KOÇ, Gülden BÖLÜK, Fatma Banu BEYAZ SİPAHİ 12 ∗ 𝑒𝑖𝑗 = 𝑒𝑖𝑗 + 𝑤𝑗 𝑛𝑖 𝑖, 𝑗 = 1,2,3 … . . , 𝑛 (5) The compensated price elasticities obtained by the Slutsky equation can be used to calculate the Hicksian compensated variation. As seen from equation (5), in order to calculate Hicksian compensated price elasticity, Marshallian own-price and income elasticity of 𝜕𝑞 𝑚 𝑞𝑖 residential electricity demand is needed. In Equation 5, 𝑛𝑖 = � 𝑖 � � � is an expenditure 𝜕𝑚 elasticity of ith commodity. This demand system can be estimated by incorporating the following parametric constraints of homogeneity, symmetry and Engel aggregation: ∑𝑗 𝑒𝑖𝑗 = −𝑛𝑖 , 𝑒𝑖𝑗 /(𝑤𝑗 + 𝑛𝑗 ) = 𝑒𝑖𝑗 /(𝑤𝑗 + 𝑛𝑖 ) and ∑𝑖 𝑤𝑖 𝑛𝑖 = 1 , where 𝑤𝑖 = 𝑞𝑖 𝑝𝑖 /𝑚 is the expenditure weight of ith commodity (Huang, 1993). The available residential demand models are estimated with time series data, however they can only provide aggregated elasticities for both price and income. Therefore, it is necessary to decompose elasticities by income strata in order to measure the differential welfare impact of electricity price changes. To accomplish decomposition or obtain disaggregated elasticities, Marshallian own-price elasticity is calculated by taking the mean value of the own-price elasticities for residential electricity demand from the models estimated using time series data. It is assumed that household by income strata have similar Marshallian price responses. In addition, Hicksian price response is differentiated using equation (5) and disaggregated income elasticities obtained from the household demand model estimates with cross-section data by income strata. In the empirical literature, the household demand model for electricity can be specified either based on the household production theory which assumes that electricity is a derived demand of household stocks of devices such as appliances or neo-classical consumer theory which assumes that demand is a function of prices and budget constraints. There are also some studies in which both approaches for model specification have been combined. 4. Residential Electricity Demand Model and Data In this study, Working-Leser type Engel function for electricity demand was specified to obtain income elasticities by income strata. Working-Leser specification is one of the widely used methods for studying relationship between expenditure share of goods (food, electricity, transportation, health, etc) and household characteristics (Deaton and Muelbauer, 1980). This specification meets the following criteria: i) it is suitable for multiple types of goods, ii) it allows for increasing, decreasing and constant marginal properties to spend over a The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey 13 wide range expenditure levels and iii) it satisfies the additivity criterion, in other words, the sum of marginal propensities for all goods should equal unity (Bandyopadhyay, Guzman and Lendelvo, 2010). Since incomes vary substantially across individuals or households, therefore income elasticity may vary across goods. The income effect for individuals at different space on the income distribution must be fully captured for a demand model to predict responses to price increases (Banks, Blındell and Lewbel, 1997). The Engel Curve analysis has been accepted as an important tool in understanding the dynamics of houshold welfare. For example it has proved useful in the modelling of income distribution and the tax applications on prices (Castaldo and Reilly, 2007; Dai, Masui, Matsuoaka and Fujimori, 2012; Brau and Florio, 2001). Moreover, a complete description of consumer behavior sufficient for welfare analysis requires a specification of both Engel curve and relative price effects consistent with utility maximization (Banks et al, 1997). In Working-Leser model, each share of the goods and services item is simply a linear function of the log of total expenditure on all the goods and services. This model can be extended to include household demographic characteristics and household location which have an influence on all goods and services items in the model (Sirirotjanaput, 2012). The general functional form of Working-Leser can be expressed as follows: 𝑤𝑖𝑗 = 𝛼0 + 𝛽𝑖 𝑙𝑛𝑋𝑗 + ∑𝑘 𝛾𝑖𝑘 𝑍𝑘𝑗 + 𝜀𝑖 (6) where 𝑤𝑖𝑗 is the share of the ith good or service within total goods and services expenditure budget of the jth household, Xj is the log of the jth household total expenditure adjusted by adult equivalence scale , Zkj are set of jth household characteristics that may influence demand and 𝜀𝑖 is random disturbances assumed with zero mean and constant variance. β and γ are estimated regression coefficients (Sirirotjanaput, 2012). The income elasticity (or expenditure as a proxy), is generally differentiated through the shifting slope of household income by dummy variables for all income strata. In this study, the general forms of the household demand model in the form of Engel functions are specified as follows; 𝑤𝑖𝑗 = 𝛼0 + 𝛽𝑖 𝑙𝑛𝑌𝑗 + 𝛾1 ∑5𝑗=2 𝐿𝑛𝑌 ∗ 𝐷𝑗 + 𝛾2 𝐿𝐴𝐸𝑆 + 𝛾3 ∑5𝑗=2 𝐸𝐷𝑗 + 𝛾4 𝐷𝑊 + 𝛾5 𝐿𝐶 + 𝛾6 𝑆𝐷 + 𝜀𝑖 (7) where; 𝑤𝑖𝑗 is the budget share of electricity expenditure within jth household monthly consumption expenditure, LnY is the log of jth household monthly income, LnY*D stands for 14 A. Ali KOÇ, Gülden BÖLÜK, Fatma Banu BEYAZ SİPAHİ LnY*D2, LnY*D3, LnY*D4 and LnY*D5 which are interaction variables of household income with lowest, second lowest, medium, medium-high and higher income strata, respectively (i.e. D2 stands for the second lowest), LAES is the log of household size adjusted to the adult equivalent scale (OECD Equivalence Scale) 7, EDj is the dummy variable for the education level of jth household head (ED1, ED2, ED3, ED4 and ED5 indicate illiterate, primary school, secondary school, high school and higher education degrees owner respectively), DW is the dummy variable of dishwasher owner status of the jth household (DW=1, if the household owned a dishwasher), LC is the dummy variable for location where jth household is living (urban=1), SD is the dummy variable for seasonality (winter months =January, February, December=1). The household budget survey data (2007, 2008 and 2009) obtained from TurkStat was used to estimate the residential electricity demand model specified in the equations given above (Equations 6 and 7). It was not possible to estimate the price responses since the data did not include price variables for the household level. Furthermore, nominal prices started to adjust from the beginning of 2008 and then only changed a few times during the period considered (2007-2009). Therefore, the variability of prices is limited to obtain price responses if it is included in the demand models. The budget survey data of TurkStat consist of 8548, 8550 and 10046 observations for the 2007, 2008 and 2009 surveys, respectively. The reporting rates of electricity expenditures by household were 81, 76 and 76 percent for the same years, respectively. In this study, since the remaining observations are at a high percent of total observations, the omitted variables have been treated as if they do not cause bias in the model (see Table 2). However, Zhang (2011) tested whether omitted variable bias existed due to non-electricity expenditure reporting household with TurkStat “2008 and 2009 budget survey data” and rejected null hypothesis. The descriptive statistics and ANOVA test for the variable used in the demand model are reported in Table 2 and Table 3. As seen in Table 3, F statistics confirm that the mean electricity expenditure is statistically different according to the income strata, location, household size, education level of household head and dishwasher owner status. Therefore, these variables can be used as explanatory variables in the demand model specified in equations 6 and 7. 7 The number of adults for each household size is calculated by using the coefficients which are called equivalence scale. The OECD measure which is 1 for the reference person of the household, 0.5 for household members aged 14 and over, 0.3 for household members less than age 14 is used. The equivalence measure enables comparisons between households with different size and structure (TurkStat, 2012). The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey 15 5. Model Results and Discussion The model associated with the 2007 survey data indicates that 8 coefficients including income are significant at the 1 percent level and two variables are significant at the 10 percent level. Similar results are obtained with 2008 and 2009 survey data. However, 9 and 12 estimated coefficients are significant at the 1 percent level for 2008 and 2009, respectively. Therefore, it can be said that majority of estimated coefficients of the model for each year are statistically significant. The results obtained with the different surveys conducted in different years are very similar in terms of magnitude and sign of coefficients. The income elasticities of electricity calculated from the model estimated using the survey conducted in 2007, 2008 and 2009 confirm the necessity of electricity at each income strata (range from 0.74 to 0.91) and decrease as the economic status of household increases. On the other hand, income elasticity obtained from the model estimated using the 2009 budget survey is moderately higher than the income elasticity for the “2007 budget survey data”. Estimated income elasticities are comparable with elasticities which are reported in electricity demand literature (Table 1). As frequently encountered in empirical econometric studies with cross-section data, error variance is not homoscedastic among observations, which seriously affects the result of the tested hypothesis. Whether or not the variance of estimated models is homoscedastic was examined using the White General Heteroscedasticity test. Since the chi-square test statistics were found to be higher than the critical value (see Table 4), the White General Heteroscedasticity test rejects the null hypothesis. Hence, the variance of the estimated models is not homoscedastic. One of the remedies applied in empirical studies to alleviate the heteroscedasticity issue is White’s heteroscedasticity-corrected standards errors procedure (Gujarati, Porter and Gunasekar 2011, pp.434). In this study, the models are estimated with the White covariance correction procedure. As expected, the determination coefficients are low which is a common result obtained with cross-section data. Studies with cross-section data rely on the significances of estimated parameters rather than determination coefficients for goodness of fit statistics. Since majority of estimated coefficients are significant at either the 1 percent, 5 percent or 10 percent level (very few), we can use the estimated model parameters for policy analysis. In the following part of the paper, the impact of residential electricity price (tariff) escalation on household welfare for different income strata is 16 A. Ali KOÇ, Gülden BÖLÜK, Fatma Banu BEYAZ SİPAHİ calculated using the compensated variation employing the formula given in Eq.4 (Huang and Huang, 2009). Table 4: Household Electricity Demand Model Estimation Results Explanatory Variables Constant Log of Household Monthly Income (LY) LPCY*D2 for Second Income Strata LPCY*D3 for Third Income Strata LPCY*D4 for Fourth Income Strata LPCY *D5 for Fifth Income Strata Log of Household Adult Equivalent Size (LAES) Dummy for Dishwasher Owner Status Education Level of Household Head (ED2) Education Level of Household Head (ED3) Education Level of Household Head (ED4) Education Level of Household Head (ED5) Dummy for Location (LC=1 Urban) Dummy for Seasonality (Winter Months;1,2,12) R2 Observations (n) White’s general heteroscadasticity test 2007 2008 2009 Household Monthly Electricity Expenditure Share (Wi) 0.0098 0.0931 0.0991 (12.58)* (8.52)* (9.47)* -0.0086 -0.0045 -0.0052 (6.99)* (2.62)* (3.16)* -0.0008 -0.0001 -0.0010 (3.49)* (3.32)* (3.49)* -0.0008 -0.0012 -0.0013 (3.04)* (3.60)* (4.12)* -0.0007 -0.0016 -0.0016 (2.62)* (4.11)* (4.39)* -0.0005 -0.0019 -0.0019 (1.72)*** (3.93)* (4.25)* 0.0033 0.0019 0.0026 (2.89)* (1.60) (2.43)** 0.0021 0.0037 0.0046 (3.52)* (0.92) (1.28) 0.0006 -0.0030 -0.0037 (0.51) (2.08)** (2.66)* -0.0022 -0.0036 -0.0041 (1.62) (2.20)** (2.57)* -0.0017 -0.0032 -0.0040 (1.39) (1.96)** (2.59)* -0.0018 -0.0045 -0.0050 (1.30) (2.69)* (3.21)* -0.0093 -0.0140 -0.015 (10.96)* (11.94)* (13.71)* 0.0013 0.0049 0.0061 (1.89)*** (4.96)* (6.99)* 0.115 0.129 0.144 6891 6489 7642 200.9 153.0 7591.5 Income Elasticities by Income Strata Lowest Second Lowest Medium Medium High Highest 0.797 0.702 0.680 0.635 0.552 0.880 0.850 0.785 0.739 0.660 0.912 0.864 0.839 0.807 0.744 *, ** and *** indicate that the coefficients are significant at 1%, 5% and 10% level. Critical value of Chi-square is 23.7 and 27.6 for 14 and 17 degree of freedom at 5% level. The values in the parenthesis are t statistics. The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey 17 As explained before, one of the key parameters for measuring welfare change with CV is compensated own-price elasticity, which can be obtained by the Slutsky decomposition of price changes. The key parameter in this study is income elasticity, since Marshallian ownprice elasticity is computed with meta analysis from time series electricity demand model studies reported in the Table 1, assuming all households in all income strata have the same Marshallian price response. However, the mean value of own-price elasticity computed from different demand studies with time series data for residential electricity demand in Turkey is 0.49 which indicates that electricity is a moderately inelastic good in Turkey. The estimated models have been used to compute differentiated income elasticity by income strata. Therefore, the key parameter in this study is income elasticity. The income elasticities were obtained from the share dependent model from the viewpoint of aforementioned theoretical basis of the model (Bandyopadhyay et al, 2010). Table 5: Welfare Impact of Residential Electricity Price Tariff Changes Income Si* Si Si (2007) (2008) (2009) Strata Welfare Welfare % of Hicks (CV) (CV) Expend Electricity Price 2009/08 2009/07 2007** Expend*** Elasticity First 4.2 3.7 5.9 0.71 1.6 16.9 9.2 -0.45 Second 3.1 3.1 4.6 0.89 1.8 18.2 9.8 -0.46 Third 2.9 2.7 4.0 1.05 2.2 22.0 10.1 -0.47 Fourth 2.5 2.3 3.5 1.17 2.6 24.8 10.3 -0.47 Fifth 2.0 1.9 2.8 1.40 3.2 29.6 10.7 -0.48 Means 3.0 2.7 4.2 1.04 2.2 22.3 10.1 -0.46 * Si is percentage of electricity expenditure within total household monthly expenditure. ** Electricity expenditure is calculated with deflated price (CPI, 2003=100). ** *indicates that the welfare loss (CV) in 2009 as a percentage of electricity expenditure with constant price in 2007. The welfare impact result of electricity tariff escalation on households in the income strata is given in Table 5. As seen, welfare change is remarkable when compared with the baseline average monthly electricity expenditure. However, from 2007 to 2009, welfare declined due to price escalation to be 9.2 %, 9.8 %, 10.1 %, 10.3 % and 10.7 %, according to the ascending order of income strata from the lowest to the highest. It can be expected that the impact will be higher as a percentage of baseline expenditure with deflated prices if the A. Ali KOÇ, Gülden BÖLÜK, Fatma Banu BEYAZ SİPAHİ 18 analysis is extended up to the end of 2012. However, nominal prices have increased around sixty percent since July 2008. Our results are in line with the findings of the previous studies pointing out the welfare loss in case of positive price shocks (See Bagdadioglu, Basaran, and Waddams Price, 2007; Zhang, 2011; Akkemik, 2009). 6. Conclusion The restructuring process of electricity market initiated in 2001 also envisaged rationalization in electricity tariff rates and removing cross subsidies. The rationalization in electricity tariffs has not followed the restructuring process simultaneously. Although the government-regulated retail price of electricity remained constant in nominal terms (declined in real terms) during 2003-2007, it has been escalating since July 2008. However, the nominal retail tariff of electricity was adjusted in several steps and the nominal price increased 59 percent (13.6 % in real terms) from July 2008 to February 2013. The real price change would be higher (33%) if January 2007 and December 2009 period was considered. This study analyzed the welfare impact of residential electricity tariff adjustment on households in different income strata. Empirical analysis consists of the estimation of the household electricity demand model with TurkStat 2007, 2008 and 2009 budget survey data by income strata and Hicksian compensating measures of welfare due to price change. The income elasticities by income strata obtained from the demand models with the budget survey conducted in different years are found to be close to each other, confirming that electricity is a necessity good in Turkey. Furthermore, these elasticities decrease as income goes up (ranging from 0.74 to 0.91 for income strata). The magnitude of the income elasticities by income strata is much lower than the long-run income elasticities obtained by previous time series econometric studies. The income elasticity by income strata derived from the estimated residential demand model and the mean value of Marshallian long-run own-price elasticity of residential electricity obtained by previous time series econometric model studies for Turkey were used to obtain Hicksian own-price elasticities via Slutsky decomposition for each income strata. The welfare impact relies on Hicks compensated variation (CV), which indicated that welfare loss of households from 2007 to 2009 was about 9-10 percent by income strata as compared with the pre-tariff adjustment period. It is expected that the welfare losses would be larger if the analysis periods extended to 2012. The main contribution of this study is to combine time series and cross section parameters, and use it to differentiate The Impact of Economic Crisis and Tariff Adjustment on Residential Electricity Demand in Turkey 19 elasticities and calculate welfare impact by income group. It will be possible to estimate direct price elasticities by income strata using pooling or panel data if this data is provided by TurkStat which will enrich results and increase reliability of welfare measure. The data and empirical results indicate that electricity price adjustment increased budget share of electricity in total expenditure of the households. 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