Research Methodology
The models using statistical data are divided into three groups. Some models use the "time series" or in other words a relatively long period of several years can be estimated. Other models based on "data point" to estimate the variables in a given time period, say a week, a month or a year in the different units are examined. A third model, which is also used in this research, estimations based on "panel data". In this way, a series of cross-sectional units (eg firms) are considered in the past few years. Given that the merged observations lead to greater volatility, less among the explanatory variables, more degrees of freedom to estimate the total efficiency is higher, relative to panel studies and time-series crosssectional studies have the advantage (Baltaji, 1995).
Financial Ratios data firms in Tehran Stock Exchange for the financial statement that is accessible through the application of innovative outcomes, has been achieved. Companies' stock prices to calculate stock returns are obtained from the site of the Tehran Stock Exchange. The collected data into Excel Software page range and preliminary calculations, the variables in this application has been made. After calculating variables for final analysis Eviews software is used. Also suitable for examining the statistical methods employed and better Hausman test and F bound.