This research is aimed to describe the application of robust regression and its advantages over the least square regression method in analyzing financial data. To do this, relationship between earning per share, book value of equity per share and share price as price model and earning per share, annual change of earning per share and return of stock as return model is discussed using both robust and least square regressions, and finally the outcomes are compared. Comparing the results from the robust regression and the least square regression shows that the former can provide the possibility of a better and more realistic analysis owing to eliminating or reducing the contribution of outliers and influential data. Therefore, robust regression is recommended for getting more precise results in financial data analysis., {"references":["Azar, A. and Momeni,M., Business statistics, 3th Edition, Samt\nPublications,Tehran, 2008.","Anderson, D. R. and Sweeney, D. J, Statistics for Business and\nEconomics, 7th edition, Williams, T.A., South western college, 1998.","Bamett, V. and Lewis. T, Outliers in Statistical data, Third ed., Wiley,\nChichester, 1993.","Chatterjee, S. and Hadi A.S., Regression analysis by example, 4th\nedition, Wiley, New Jersey, 2006.","Chatterjee, S. and Hadi A.S., \"Influential Observations, High Leverage\nPoints, and Outliers in Linear Regression\", Statical Science, Vol. 1, No.\n3, 1986, pp.379-416.","Chatterjee, S. and M├ñchler, M., \"Robust regression: A weighted least\nsquares approach\", Communications in Statistics ÔÇö Theory and\nMethods, No.26, 1997, pp.1381-1394.","Chen, C., \"Robust Regression and Outlier Detection with the\nROBUSTREG Procedure\", presented at SUGI, No.27, 2002, pp.265.","Cook, R. D., \"Detection of influential observations in linear regression\",\nTechnometrics, No. 19,1977, pp.15-18.","Easton, P., & Harris. T., \"Earnings as an Explanatory Variable for\nReturns\", Journal of Accounting Research, 1991, No.29, pp.19-36.\n[10] Field, C. and Zhou, J., \"Confidence intervals based on robust\nregression\", Journal of Statistical Planning and Inference, No.115, 2003,\npp.425 - 439.\n[11] Gujarati, D.N., Basic Econometrics, Third edition, Mc Graw-Hill\ninternational edition, 1995.\n[12] Hoaglin,D.C. and Welsch,R.E., \"The hat matrix in regressin and\nANOVA\", The American Statistician, No.32, 1978, pp.17-22.\n[13] Hodges J.L., Proc. Fifth Berkeley Symp. Math. Stat. Probab.,No.1, 1967,\npp.163-168. http: // www. 2sas . com / proceedings /sugi27/pdf.\n[14] Liang,Y.Z. and Kvalheim O.M., \"Robust methods for multivariate\nanalysis - a tutorial review\", Chemometrics and Intelligent Laboratory\nSystems, No.32, 1996, pp.1-10.\n[15] Martin, R. D. \"Robust Statistics with the S-Plus Robust Library and\nFinancial Applications\", Vol. 1 and 2, Insightful Corp Presentation, New\nYork, NY, 2002, No.17-18.\n[16] Neter, J. and Kunter, M. H., Nachtsheim, C. J. and Wasserman. W.,\nApplied Linear Regression Models, Third edition, Mc Graw-Hill, USA,\n1996.\n[17] Ohlson, J., \"Earnings, Book Values, and Dividends in Equity\nValuation\", Contemporary Accounting Research, (Spring), 1995,\npp.661-687.\n[18] Preminger, A. and Franck, R., \"Forecasting exchange rates: A robust\nregression approach\", International Journal of Forecasting, No.23, 2007,\npp.71- 84.\n[19] Rousseeuw P. J. and Zomeren B. C., \"A comparison of some quick\nalgorithms for robust regression\", Computational Statistics & Data\nAnalysis, Vol.14, 1992, pp.107-116.\n[20] Rousseeuw, P.J. and Leroy, A.M., Robust Regression and Outlier\nDetection, Wiley, New York, 1987.\n[21] Rousseeuw, P.J. and Van Driessen, K., \"Computing LTS Regression for\nLarge Data Sets\", Technical Report, University of Antwerp, 1998.\n[22] Rousseeuw, P.J., \"Least Median of Squares Regression\", Journal of the\nAmerican Statistical Association, No.79, 1984, pp. 871-880.\n[23] Yaffee, R. A., \"Robust Regression Analysis: Some Popular\nStatistical Package Options\", Statistics, Social Science, and Mapping\nGroup,Academic Computing Ser, 2002.\nwww.nyu.edu/its/socsci/docs/RobustReg2.pdf."]}