가락시장 채소가격의 요일효과에 관한 연구

A Study on the Day-of-the-Week Effects in Garak Vegetable Markets

The objectives of this study are to determine the existence of the day-of-the-week effects in vegetable prices at Garak wholesale market and to investigate the reasons of the day-of-the-week effects. Analysis is conducted on chinese cabbage, red pepper, garlic, onion, carrot and green onion, over the period from January 1995 through December 2003. The multiple regression model with dummy variables is estimated by generalized least squares(GLS) to obtain the average value of daily logarithmic price changes. It is found that significant day-of-the-week effects are present for chinese cabbage, onion and green onion prices, with the pattern of positive price changes on Monday or Tuesday and negative price changes on Saturday. The average daily prices of chinese cabbage, onion and green onion are generally higher in the beginning of the week and lower on weekend. The results imply that producers could make higher returns by shipping their vegetables in the beginning of the week rather than on weekend. The day-of-the-week effects are explained by the degree of perishability, buyers and wholesalers purchasing pattern, diminishing demand on weekend, and decreased supply on Sunday due to traffic congestion.