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โครงการหนังสืออิเล็กทรอนิกส์ด้านการเกษตร เฉลิมพระเกียรติพระบาทสมเด็จพระเจ้าอยู่หัว

Effects of Natural Disasters on Structural Changes in Thailand’s Economic Crop Prices

Abstract

The project “Effects of Natural Disasters on Structural Changes in Thailand’s Economic Crop

Prices” examines effects of natural disasters on structural changes of crop prices including jasmine 105

paddy, unsmoked rubber sheet No. 3, cassava root and oil palm (>15 kg fresh fruit branch). The objectives
of the study includes (1) investigating the potential existence of structural changes in Thailand’s economics

crop prices and examine the pattern of the structural changes across the commodity markets; (2) identify an

association between identified break points and actual events i.e. determine whether the structural changes
are caused by natural disasters and; (3) determining channels in which natural disasters affect crop prices

such as Gross Domestic Product, farming productivities and production quantities.

To estimate and test the potential existence of structural changes in the crop prices, this study
adopted the multiple structural change model proposed by Bai and Perron (1998, 2003). Crop price data

used in this study are Thailand’s monthly farm gate price data provided by the Office of Agricultural

Economics. The study finds that there exist structural changes in crop prices. There are several factors
inducing structural changes in the crop prices such as the world economy, food crisis, weather fluctuation,

natural disasters and government policies. The results also show that each of the structural changes in crop

price is not caused by a single factor, but a combination of several factors acting at once. In addition, for

some structural changes, natural disasters may not be a part of the causes.
To further test for the statistical significance of the effects of natural disasters on structural changes

in crop prices, this study also applied the Interrupted Time-series Analysis. In the case of unsmoked rubber

sheet price, the results show that the 2006 and 2010 flood had a statistically significant positive effect on
the structural change in the price. The 2010 flood also had a statistically significant positive effect on the

structural change in the price of oil palm. However, the price dropped after the 2011 flood. In addition, the

2010 flood caused a significant increase in the price of cassava root and the 2002 flood caused a significant

increase in the price of jasmine paddy.
To determine channels in which natural disasters affect crop prices, this study examined two cases

including (1) the supply side analysis, which is to test the effects of natural disasters in Thailand on the

quantity of each of the crops using the Interruptible Time-series Analysis and (2) the demand side analysis,
which is to estimate the short-run and long-run relationships between domestic crop prices in Thailand and

commodity futures prices in foreign countries using the Markov-Switching Error-Correction Model (MD-

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