Demand and nutrient elasticities of egg consumption: Evidence from Saudi Arabia

Alsaad, Dana; Al Mahish, Mohammed A. Article Demand and nutrient elasticities of egg consumption: Evidence from Saudi Arabia Economies Provided in Cooperation with: MDPI – Multidisciplinary Digital Publishing Institute, Basel Suggested Citation: Alsaad, Dana; Al Mahish, Mohammed A. (2024) : Demand and nutrient elasticities of egg consumption: Evidence from Saudi Arabia, Economies, ISSN 2227-7099, MDPI, Basel, Vol. 12, Iss. 9, pp. 1-14, https://doi.org/10.3390/economies12090245 This Version is available at: https://hdl.handle.net/10419/329172 Standard-Nutzungsbedingungen: Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden. Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. 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Economies 12: 245. https://doi.org/10.3390/ economies12090245 Academic Editor: Sanzidur Rahman Received: 13 June 2024 Revised: 18 August 2024 Accepted: 5 September 2024 Published: 11 September 2024 Copyright: © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). economies Article Demand and Nutrient Elasticities of Egg Consumption: Evidence from Saudi Arabia Dana Alsaad and Mohammed Al-Mahish * Department of Agribusiness & Consumer Science, College of Agriculture and Food Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia *Correspondence: [email protected] Abstract: Chicken eggs are a staple food widely consumed directly or indirectly (as an ingredient in other food items) in Saudi Arabia. Due to the importance of eggs in Saudi consumers’ diet, this study aimed to determine the sociodemographic factors affecting Saudi consumer demand for eggs and how changes in egg prices and consumer income may influence dietary intake derived from eggs. This study analyzes survey data from 466 respondents. We used a double-log demand model to obtain the price and income elasticities of egg demand. The results show that the price elasticity of egg demand is negative and inelastic, indicating that changes in egg price have a small influence on egg demand. Additionally, income elasticity is positive and <1, implying that eggs are a necessary food item. Cross-price elasticities show that cheese and milk complement egg consumption. Meanwhile, cornflakes (a breakfast cereal) were found to be a good substitute for eggs. Furthermore, the results show that consumer demand for eggs is expected to increase as household size increases. Women exhibited a higher demand for eggs, compared with men. Nutrient income elasticity shows that an increase in consumer income increases protein, fat, and calorie intake from eggs. Nutrient price elasticity shows that an increase in egg price has the greatest negative influence on protein intake, resulting from a decrease in egg consumption. This study recommends that decision makers actively monitor egg prices and take all necessary actions to prevent spikes in egg prices, as this will improve nutritional and food security and help consumers maintain a stable protein intake from egg consumption. Keywords: demand elasticity; egg consumption; nutrient elasticity 1. Introduction The lack of adequate food can result in malnutrition and famine. Accordingly, the food sector plays an important role in economic activities worldwide. The volatility of food prices resulting from a fluctuating food supply affects consumers’ acquisition of food and, consequently, their nutrient intake derived from food. Chicken eggs have been an animal food source consumed by humans for thousands of years worldwide. Eggs have been considered as one of the staple food products that are part of most people’s diet worldwide (Food and Agriculture Organization 1995). Nonetheless, eggs can be consumed as complementary food in babies’ diet (Faber et al. 2022). They are an essential source of vitamins, minerals, and proteins, which makes them an important and indispensable food component, especially for low-income families. Moreover, eggs contain essential amino acids in appropriate proportions to meet human requirements (Ruxton et al. 2010;Matsuoka and Sugano 2022;Puglisi and Fernandez 2022). Owing to the global importance of chicken eggs, global production has increased by 69%, compared to that twenty years ago, reaching a production of 87 million/ton in 2020 (Food and Agriculture Organization 2022). The total annual domestic egg production in Saudi Arabia constitutes 0.4% of the total global production at a rate of 315 thousand/ton per year (Ministry of Environment Water and Agriculture 2019). One report (Ministry of Economies 2024,12, 245. https://doi.org/10.3390/economies12090245 https://www.mdpi.com/journal/economies Economies 2024,12, 245 2 of 14 Environment Water and Agriculture 2023) revealed that local agricultural products have shown an increase in production capacity over the past few years—with one of the most important ones being the acceleration of egg production, which has contributed significantly to achieving food security in Saudi Arabia. Egg production achieved high completion rates in 2023, as 123 chicken-laying projects were implemented in Saudi Arabia, with a sufficiency rate of 126%, surpassing production rates from previous years. In addition to this increase in production, per capita egg consumption in Saudi Arabia reached 9.07 kg in 2021 (Helgi Library 2023). It imported more than half a million cartons, equivalent to more than 183 million eggs, to balance supply in the local market (Saudi Agricultural and Livestock Investment Company 2020). However, despite the increase in egg supply, the price of the 30-egg tray has increased by 44.672%, compared with that ten years ago (General Authority for Statistics—GASTAT 2024). Figure 1shows that the average price of egg trays increased to new levels in 2020–2023. This increase in egg price can be attributed to the increase in feed price (Çevrimli et al. 2024;Muhammad et al. 2023), avian flu (Jiménez 2023), and the levy of a 15% value-added tax (VAT) in 2020 following the COVID-19 pandemic (Bogari 2020;Shukeri and Alfordy 2021). Economies 2024, 12, x FOR PEER REVIEW 2 of 15 report (MEWA 2023) revealed that local agricultural products have shown an increase in production capacity over the past few years—with one of the most important ones being the acceleration of egg production, which has contributed significantly to achieving food security in Saudi Arabia. Egg production achieved high completion rates in 2023, as 123 chicken-laying projects were implemented in Saudi Arabia, with a sufficiency rate of 126%, surpassing production rates from previous years. In addition to this increase in production, per capita egg consumption in Saudi Arabia reached 9.07 kg in 2021 (Helgi Library 2023). It imported more than half a million cartons, equivalent to more than 183 million eggs, to balance supply in the local market (Saudi Agricultural and Livestock Investment Company 2020). However, despite the increase in egg supply, the price of the 30-egg tray has increased by 44.672%, compared with that ten years ago (GASTAT 2024). Figure 1 shows that the average price of egg trays increased to new levels in 2020–2023. This increase in egg price can be attributed to the increase in feed price (Çevrimli et al. 2024; Muhammad et al. 2023), avian flu (Jiménez 2023), and the levy of a 15% value-added tax (VAT) in 2020 following the COVID-19 pandemic (Bogari 2020; Shukeri and Alfordy 2021). Figure 1. Average real price of a 30-egg tray (local eggs) in SAR (2012–2022). Source: Authors’ calculation based on GASTAT data. Therefore, the simultaneous increase in supply and prices makes the contribution of eggs to maintaining a sustainable agricultural market unclear, especially since the average Saudi individual consumes 9.1 kg of chicken eggs annually (MEWA 2023)—approximately 2.75 eggs per person/week. This shows a decline in Saudi individuals’ consumption of the recommended quantities of food rations, according to data from the Healthy Food Palm (FAO 2023; Ministry of Health 2023). This study investigated the factors influencing egg consumption in Saudi Arabia. Additionally, this study aimed to demonstrate how changes in egg prices and consumer income influence consumers’ nutrient intake derived from egg consumption. Specifically, it estimates price and income elasticities to measure egg demand’s sensitivity to changes 10.56 14.18 13.35 13.73 12.49 11.52 13.59 12.49 15.75 15.36 18.53 17.96 0.00 5.00 10.00 15.00 20.00 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 Constant Price Year Figure 1. Average real price of a 30-egg tray (local eggs) in SAR (2012–2022). Source: Authors’ calculation based on GASTAT data. Therefore, the simultaneous increase in supply and prices makes the contribution of eggs to maintaining a sustainable agricultural market unclear, especially since the average Saudi individual consumes 9.1 kg of chicken eggs annually (Ministry of Environment Water and Agriculture 2023)—approximately 2.75 eggs per person/week. This shows a decline in Saudi individuals’ consumption of the recommended quantities of food rations, according to data from the Healthy Food Palm (Food and Agriculture Organization 2023;Ministry of Health 2023). This study investigated the factors influencing egg consumption in Saudi Arabia. Additionally, this study aimed to demonstrate how changes in egg prices and consumer income influence consumers’ nutrient intake derived from egg consumption. Specifically, it Economies 2024,12, 245 3 of 14 estimates price and income elasticities to measure egg demand’s sensitivity to changes in price and consumer income. Further, it examines the effect of household sociodemographic characteristics on egg consumption. Finally, it concludes by estimating the nutritional elasticities of calories, proteins, carbohydrates, and total fat obtained from egg consumption. Food consumption is one of the most important factors contributing to the continuation of business cycles. Owing to the COVID-19 pandemic and international conflicts, the cost of inputs used in food production and supply have drastically increased, resulting in a spike in food prices. However, the International Monetary Fund (2022) indicated that the global economy is resisting the increase in food prices. Meanwhile, eggs were among the food items affected by price hikes. Therefore, previous studies in other countries were reviewed for enrichment, contrast, identification of differences, and generation of ideas. In Latin America, specifically in the Costa Rican context, Dal et al. (2022) aimed to analyze the price elasticity of the main food categories, determine the impact of consumer demand for food, anticipate changes in the quantity demanded, and provide recommendations from the perspective of cognitive behavioral therapy according to 11 food groups. The average expenditure on milk, cheese, and egg products was 14.69% of the total food expenditure, while 16.67% of families did not consume eggs, milk, or cheese. The income elasticity for the egg, milk, and cheese groups was 1.01, which means it was a luxury good for families. The uncompensated price of elasticity of the milk, eggs, and cheese groups is − 1.03, meaning that this group’s demand is price-elastic. Regarding uncompensated cross-price elasticity, an increase in the price of eggs, cheese, and milk leads to an increase in the consumption of oils and fats by 3.1%. In the United States, the demand for pastured eggs was estimated to be price-inelastic, and pastured eggs were classified as luxury goods (Bakhtavoryan et al. 2023). Bakhtavoryan et al. (2021) estimated the demand for omega-3, organic, cage-free, and conventional eggs using the exact affine stone index model. Expenditure elasticity was <1, showing that all egg types were considered necessary. Moreover, the estimated own-price elasticity was <1 in absolute value for omega-3 and conventional eggs, showing that the demand for these types of eggs was price-inelastic. The uncompensated and compensated cross-price elasticities showed that traditional eggs were a substitute for all types of eggs. Said study’s results also showed that larger households spent more on organic and conventional eggs, compared with smaller households. Further, household heads with a high school degree or a lower degree spent more on conventional eggs, compared with college-educated household heads. In an old study by Blaylock and Burbee (1985), the impact of prices, income, and household characteristics on the demand for eggs was estimated using data obtained from the United States Department of Agriculture’s food consumption survey. Its results indicated that the price elasticity of eggs was inelastic and <1. Moreover, the estimated income elasticity was negative and statistically insignificant. The authors attributed this to the fact that the demand for eggs is insensitive to changes in consumer income. Many researchers have empirically examined egg demand in East Asia. Wongmonta (2022) analyzed food consumption patterns for six food groups (rice and grains, meat and fish, eggs and dairy products, vegetables and fruits, meals at home, and meals outside the home) to determine how families respond to changes in food prices and income. The author used a household survey of rural and urban residents in Thailand. Families spent 5.2% of their income on eggs and dairy products. Family size and the ratios of elderly individuals and children in the household had a negative impact on food expenditure at the 1% significance level. The estimated expenditure elasticities ranged from 0.71 to 1.29, indicating that most food groups were normal goods. The estimated uncompensated ownprice elasticity for egg and dairy groups was − 0.946, while the compensated own-price elasticity was − 0.894. Rathnayaka et al. (2021) analyzed the demand for foods derived from animal sources (chicken, meat, eggs, and fish) to estimate income and price elasticities in seven Asian regions: Hong Kong, Japan, the Philippines, Singapore, Sri Lanka, Taiwan, and Thailand. Their results revealed, through income elasticity, that animal-derived foods were necessities in all regions, except for Taiwan. The conditional price elasticity of eggs Economies 2024,12, 245 4 of 14 ranged from − 0.029 in Japan to − 0.650 in Thailand, indicating that eggs were price-inelastic. Conversely, the unconditional price elasticity of eggs in Sri Lanka was − 1.575, which means the demand is price-elastic. Siregar et al. (2021) analyzed the effect of consumer income and substitute products (tempeh, tofu, and chicken meat) on the demand for chicken eggs. The sample comprised 60 participants residing in Makassar, Indonesia. Their results showed that tempeh, tofu, and chicken meat significantly affected egg demand. The study predicted that if income increased by IDR 100,000/month, the demand for eggs would increase by 0.007208 trays per month. Nafaati et al. (2021) analyzed the price elasticity of demand for hybrid chicken eggs in Pamekasan, Indonesia. Their results showed that the price elasticity of demand for hybrid chicken eggs was price-inelastic. In another study (Nikmatul et al. 2020) conducted in Indonesia, the ownand cross-price elasticities of eggs were estimated using the quadratic almost ideal demand system (QUAIDS). Their results showed that eggs were a normal good and families reacted to increments in animal-source food prices by switching to cheaper animal foods, which worsened their nutritional status, especially among low-income consumers. A previous study (Astaman et al. 2020) explained the factors affecting the demand for chicken eggs in Berengkanaya, Indonesia. They surveyed 60 family respondents through observations, interviews, and questionnaires. Data were analyzed using a multiple linear regression model. Their results showed that the factors influencing egg demand were egg and broiler chicken prices. Additionally, (Febrianto et al. 2013) aimed to determine the factors affecting egg prices in Malang, Indonesia, using a multiple linear regression model. The results showed that eggs were both price-elastic and -inelastic. Regarding the results of the cross-elasticity of demand, the authors concluded that other food items did not function as substitutes for eggs. Finally, said study showed that household size and education affected egg demand. Hovhannisyan and Devadoss (2020) examined the impact of urbanization on food demand and modeled the components of supply and demand in China through a national survey of urban households. The expenditure elasticity for eggs was 1.039, indicating that eggs were a luxury good. As for the uncompensated price elasticity of eggs, it was − 0.837 and inelastic. Further, the uncompensated cross-price elasticity between eggs and vegetables was positive, implying that they are substitutes. The cross-price elasticity between eggs and legumes was negative, indicating that they are complementary. Jiang et al. (2015) evaluated the impact of urban economic development on the change in demand for 10 food commodities in China. The income elasticity of the demand for eggs was 1.183, indicating that eggs were luxury goods for residents of major cities, whereas for residents of medium-sized cities, eggs were identified as necessary. The uncompensated price elasticity of eggs for residents of major cities was − 0.553, while that for residents of medium-sized cities was − 0.804, which means that eggs are an inelastic good in both cities. In Europe, Kralik et al. (2020) examined the factors affecting egg consumption in Croatia. Their sample size was 200 participants. They focused on egg quality indicators and compared the preferences of men and women through the factors affecting egg consumption. These factors were product quality, expiration date, ease of cooking, diversity of use, traces of eggs, egg price, and egg safety. Peltner and Thiele (2021) used the QUAIDS to estimate the price and income elasticities of demand for food in Germany. Their estimation of the uncompensated own-price elasticity of egg demand ( − 0.441) and the compensated price elasticity ( − 0.428) indicated that egg demand in Germany is price-inelastic. Also, the expenditure elasticity (0.838) showed that eggs are a necessity in Germany. In Lithuania, the demand for eggs was shown to be price-inelastic by Petrauskait ˙ e-Senkeviˇc (2013). Furthermore, a comparison of egg demand in Ukraine and Lithuania confirmed the fact that egg demand in both countries is price-inelastic (Petrauskait˙ e-Senkeviˇc 2020). A study conducted in Cambodia (Sary et al. 2019) analyzed food prices and household spending on food. The authors used data from 240 random households and concluded that a 1% increase in the price of eggs contributed to a 0.22% increase in spending on eggs. The price elasticity of eggs was − 0.0920; hence, it was inelastic. The cross-price- Economies 2024,12, 245 5 of 14 elasticities between eggs and both corn and vegetables were positive, indicating that they are substitute goods. There are few studies that empirically estimated egg demand in Arab countries. ElDayech et al. (2019) estimated the factors affecting egg consumption in Al-Jabal Al-Achder, Libya, based on three income categories (low, medium, and high). Their sample size was 195. Their results showed that the demand for eggs was price-inelastic. Further, the demand for eggs was inelastic for all income categories except for the middle-income category, for which demand was income-elastic. Hassan and Faied (2017) estimated the expenditure elasticities of food items, including eggs, in Beheira and Assiut, Egypt. Their results showed that eggs were a necessary food item. In spite of the aforementioned studies’ contributions, none applied a demand model to analyze egg demand in Saudi Arabia. Thus, the price and expenditure elasticities of egg demand, as well as the factors affecting consumer egg demand in Saudi Arabia, remain unclear. Thus, the present study fills this gap in the literature by revealing how consumer characteristics affect egg demand and demonstrating how changes in egg prices and consumers’ income can influence consumers’ nutrient intake derived from eggs. 2. Materials and Methods The data-collection process began in April 2022 and ended in July 2023. The required sample size was determined using a sample size calculator (SurveyMonkey 2024), based on the population size of Saudi Arabia, as follows: Sample size = ‡2×p(1−p) e2 1+‡2×p(1−p) e2N (1) N= population size (33 million). e= margin of error (equal to 5 percent). z= standardized value equal to 1.96. p= is a probability value that is between 0 and 1, and it was set to 0.50 (Bishmani 2014). Equation (1) indicates that the minimum sample size should not be <385. Data were collected by distributing an electronic questionnaire through various social media applications such as WhatsApp, Snapchat, Telegram, and Instagram since these apps are widely used in Saudi Arabia according to a report by (Communication, Space & Technology Commission—CST 2023). Although the major limitation of electronic questionnaire is concerned with residents who completely do not use the internet since they will not have a chance of inclusion in the study, the report indicated that 98.6% of Saudi males and females have access to the internet. The report also showed that the usage rate among the old population (in the age of 60 to 74 years) is in the range of 92.9% to 77.3%. Furthermore, the main limitation of data collected through questionnaires is the discrepancy between the self-reported value by respondents and the true value (Bauhoff 2014). The survey consisted of four sections. Section 1collected participants’ sociodemographic data (including gender, age, income, education, and employment status). Section 2collected general information on egg consumption and prices. Section 3collected information on other factors that may influence egg consumption. Finally, Section 4collected information on the prices and consumption of other food products that may be considered by participants as a complement or replacement for eggs. After removing unreliable and missing observations, 466 valid responses remained for analysis. Table 1shows the summary statistics for the qualitative data, while Table 2shows those for the quantitative data. Economies 2024,12, 245 6 of 14 Table 1. Summary of qualitative variables. Variable No. (%) Variable No. (%) Gender Egg allergy Male 279 (59.87%)Yes 60 (12.88%) Female 187 (40.13%)No 406 (87.12%) Household size Look for eggs in food products’ ingredient list 1–4 171 (39.04%) Yes 87 (18.67%) 5–9 255 (51.37%) No 379 (81.33%) 10–14 34 (7.75%) >15 8 (1.84%) Total 438 (100%) Residence Consume eggs in other food items City 435 (93.35%)Yes 417 (89.48%) Village 31 (6.65%)No 49 (10.52%) Social status Consume eggs during breakfast Married 227 (48.71%)Yes 427 (91.63%) Unmarried 239 (51.29%)No 39 (8.37%) Education level Consume eggs as a main course Secondary school or lower 51 (10.94%)Yes 131 (28.11%) Associate’s degree (diploma) 67(14.38%)No 335 (71.89%) Bachelor’s degree 309 (66.31%) Postgraduate education 39 (8.37%) Employment Consume eggs in snacks Student 48 (10.30%)Yes 186 (39.91%) Employee 301 (64.59%)No 280 (60.09%) Unemployed 101 (21.67%) Retired 16 (3.43%) Monthly income Consume eggs in sweets <4999 197 (42.27%)Yes 353 (75.75%) 5000–9999 116 (24.89%)No 113 (24.25%) 10,000–14,999 94 (20.17%) 15,000–18,999 30 (6.44%) >19,000 29 (6.22%) Own laying hens Consume eggs in pies and baked goods Yes 36 (7.73%)Yes 303 (65.02%) No 430 (92.27%)No 163 (34.98%) Of the 466 respondents in the final sample, 279 were men. The participants’ average age was 32 years. The household size of most respondents (51.37%) ranged between five and nine individuals. These characteristics are close with the percentages published by Saudi Census (2022a,2022b) for both males and females as well as household size in Saudi Arabia. Most respondents lived in cities (93.35%), which can be attributed to the fact that 82.1% of Saudi Arabia’s total population lives in urban areas (UN-Habitat 2024). Regarding social status, 51.29% were unmarried. Most respondents (66.31%) held a bachelor’s degree. Although participants in the labor force represented 64.59% of the sample, there were 101 unemployed participants in the sample, which can be attributed to the fact that the Saudi unemployment rate reached 8.6% in Q3/2023 according to the labor market statistics report released by (General Authority for Statistics—GASTAT 2023). Moreover, 42.27% of the sample reported a monthly income of less than SAR 4999, which is in line with the average monthly income (SAR 3618) in the private sector in Saudi Arabia in 2022 (Saudi Central Bank–SAMA 2024). Further, respondents with egg allergies represented only 12.88% of the sample, whereas 18.67% reported that they inspected the availability of eggs in other food products’ ingredient lists. Furthermore, respondents who owned laying Economies 2024,12, 245 7 of 14 hens accounted for 7.73% of the sample. Moreover, 91.63% of respondents consumed eggs during breakfast, 28.11% as a main course, 39.91% in snacks, 75.75% in sweets, and 65.02% in pies. Table 2. Summary of quantitative data. Variable Min Mean Max Sd Age 14 32.329 68 9.613 Household size 1 5.705 28 3.403 Number of egg trays 0 1.035 4 0.678 Egg expenditure (SAR) 0 18.00 100.00 8.96 Cheese quantity 0 2.872 150 9.542 Cheese expenditure (SAR) 0 21.84 250 19.52 Bread bag 0 2.578 14 1.797 Bread expenditure (SAR) 0 5.90 35.00 5.61 Tomato quantity (kilo) 0 2.459 30 2.853 Tomato expenditure (SAR) 0.00 15.17 120.00 11.67 Onion quantity (kilo) 0 2.550 20 2.750 Onion expenditure (SAR) 0.00 10.93 100.00 9.03 Lentil quantity (kilo) 0 0.690 13 1.144 Lentil expenditure (SAR) 0.00 4.44 45.00 6.42 Red beans (jar) 0 1.278 12 1.85 Bean expenditure (SAR) 0.00 5.25 60.00 6.85 Milk (liter) 0 3.897 50 4.477 Milk expenditure (SAR) 0.00 20.84 200.00 23.62 Cornflakes (gram) 0 459.495 1000 365.611 Cornflakes expenditure (SAR) 0.00 14.47 80.00 12.83 Peanut butter (gram) 0 299.098 1000 245.829 Peanut butter expenditure (SAR) 0.00 10.72 70 9.83 Additionally, regarding participants’ egg consumption, respondents usually bought one tray of eggs (30 eggs) on average. Respondents’ egg expenditure ranged from SAR 0.00 SAR to SAR 100.00, with a mean value of SAR 18.00. Table 2reports data related to the prices and quantities of complementary and substitute goods for eggs, including cheese, bread, tomatoes, onions, lentils, beans, milk, cornflakes, and peanut butter. This information is necessary because it helps estimate the cross-price elasticity of egg demand. Meat was excluded from the study design because it is mainly consumed in lunch or dinner meals and rarely consumed as a breakfast meal. Indeed, Al-Hazzaa et al. (2020) investigated breakfast consumption patterns in Saudi Arabia and indicated that spread cheese sandwiches, eggs, and cereal are the most frequently consumed breakfast items by Saudi children. Empirical estimation strategy for food demand can be mainly divided into two methods. The first method is a system demand approach, which involves estimating multiple demand equations. An example of the system demand approach is the popular almost ideal demand system (AIDS) model (Deaton and Muellbauer 1980), which is derived by applying the Shephard’s lemma on consumer cost function to obtain the Hicksian demand equations. The second method involves estimating single-equation demand model such as the famous double-log demand model (Hina et al. 2022). The main advantage of this approach is that it requires fewer parameters compared to the system demand approach. For full details regarding food demand models and their derivation, estimation, and elasticity formulas, the reader is advised to refer to Okrent and Alston (2011). A double-log demand model was used to estimate the price elasticity of the demand for eggs, income elasticity, and cross-price elasticities (Alston et al. 2002). The model can be expressed as follows: ln Qi=α+ N ∑ j=1 εijln Pij + +ηiln I+βiX+. . . +βnXn(2) Economies 2024,12, 245 8 of 14 where Q i represents the dependent variable (quantity of eggs demanded), Idenotes income (or total consumer expenditure), Pis the vector of the eggs’ own price and the cross-prices of other food items, and Xrepresents socioeconomic factors affecting egg demand. For Equation (2) to satisfy microeconomic theory, the adding-up condition must hold. Thus, we tested the adding-up process as follows: H0:ε11 +ε12 +. . . +ε1n+ηi=0 (3) Ha:ε11 +ε12 +. . . +ε1n+ηi=0 (4) The elasticities in Equation (2) are Marshallian (uncompensated). The uncompensated demand consists of income and substitution effects, whereas the compensated demand curve includes only the substitution effects (Autor 2016). Thus, the main difference between the compensated and uncompensated demand curves is whether utility or income is held constant when establishing the demand curves (Snyder et al. 2012). To obtain the Hicksian (compensated) elasticities, we used the Slutsky equation as follows: θij =εij +Sjηi(5) where θ is the compensated elasticity, Sdenotes budget shares, εij are the uncompensated price elasticities obtained from Equation (2), and ηi is the expenditure elasticity of egg demand. As eggs are an essential nutritious food item, it is important to predict how changes in egg prices and consumer income affect consumer nutrient intake obtained through egg consumption. The impact of income and price changes on dietary intake can be predicted using nutrient income and nutrient price elasticities, as follows (Faharuddin et al. 2017): EkP =∑i εij ckqi Φκ (6) EkI =∑i ηYI I cYqY Φκ (7) where EkP is the nutrient elasticity k with respect to price; EkI is the nutrient elasticity with respect to expenditure; ck is the amount of dietary intake such as calories, proteins, carbohydrates, and total fats available in egg; qi is the quantity of eggs consumed; and Φκ is the total dietary intake obtained from respondents’ regular diet. 3. Results and Discussion The first step in the double-log demand model is the examination of the null and alternative hypotheses (3) and (4). Based on the results of the F-test in Table 3, we failed to reject null hypothesis (3), implying that we do not need to impose additional restrictions in the estimation process. Table 3. F-test for an adding-up condition. F Value p-Value 0.0037 0.9616 The double-log demand model (2) was estimated using R software 4.3.2. After estimating the model, we conducted diagnostic tests to ensure that our model did not violate the least-squares assumptions. The results of the multicollinearity test (available upon request) show that all variance inflation factors were <5, implying that our model did not suffer from multicollinearity problems. We also examined the existence of influential outliers by inspecting the Cook’s d values and the Bonferroni outlier test. The Cook’s d values for all observations did not exceed 1, implying that we did not have an influential point. Moreover, the unadjusted pvalue for the Bonferroni outlier test was statistically significant at the 1%