The Trend of Fresh Vegetables Consumption in Japan by the Maximum Marginal Likelihood Method for Smoothing Serial Data

Abstract

The trend of fresh vegetables consumption in Japan was analyzed here using the Annual Reports "the family income and expenditure survey" (1963-1982). Analytical method employed was the maximum marginal likelihood method for smoothing serial data, which was characterized to provide both an estimator of an alternative smoothing regression curve and a test procedure. This method was proved to be excellent for analyzing the trend for serial data and results obtained are summarized as follows: (1) Total consumption amounts of fresh vegetables in house-hold varied from up to down in these 20 years. Maximum consumption amounts of fresh vegetables was calculated to be attained in 1973. (2) Total consumption amounts of root vegetables have linearly increased. On the other hand, those of fruit vegetables significantly varied from increase to decrease. (3) This trend of fruit vegetables consumption was not provided with a certain items but attributed to similar behaviors of 5 items among 6 items of fruit vegetables. (4)It is interesting that consumption amonuts of carrots, among root vegetables, showed steady increase. (5) Chinese cabbage, consumption amounts of which decreased most rapidly, showed accelerating the rate of decrease.