The aim of this study is to explore and compare the stochastic behavior
of price changes of onion in Jaffna district, Sri Lanka between January 1, 2008 to May
19 and June 6,2009 to December 30, 2010. The data used in this study was collected
from Jaffna weekly Vegetable markets. The sample period is divided into two periods,
i) January 1,2008 to May 19,2009. And ii) June 6,2009 to December 30,2010.
Result of this study reveals that the price behavior has changed significantly in
its stylized facts of price behavior during these study periods. The price series shows a
linear upward trend with fluctuations in the period I and an exponential trend with
fluctuations in the period II. The volatility of this price changes in the period II is
higher (SD=25.11) than the period I (SD=12.69). While the price series behave with
leptokurtic distribution (fatter tail) with outliers in the period II. the series behave with
platykurtic distribution in the period I. Estimated Kernel distributions show that both
price distributions are not normal. Phillips-Perron test shows that Price series behave as
nonstationary with I (I) in both periods. This shows that shocks have a persistent effect
on the level of the series in both periods.
The results of this study will help Modeling and forecasting the weekly price
behavior of onion
