There are some of 585 companies, the population of this research puts aside those companies under restoration, in the service business, in the consumer product business, in the resources business, in the technological business, and companies with an accounting period other than December 31 were excluded from the population sample for this research. Therefore, the sample group consists of 470 companies.
The researcher collects data from the financial statement of the companies in the Stock Exchange of Thailand (Set Smart) and from the Security and Exchange Commission from 2007 to 2012, a total of 5 years, to use in the multiple regression analysis to test the hypothesis (Zikmund, 2008).