Abstract: Regression analysis is important statistical tools for assessing the mathematical relationships among the variables in clinical research. Clinical research is increasingly based on the empirical studies and the results of these are usually presented and analyzed with statistical methods. Therefore discuss frequently used regression analysis for different type of data set to find the casual relationship among the variables under different assumptions. The regression analysis is a technique, that is appropriate to understand the association between one independent (or predictor) variable and one continuous dependent (or outcome) variables. Regression analysis may provide a researcher with an equation for a graph so that he can make predictions about research data. It is therefore an advantage for any physician or researcher he/she is familiar with the frequently used regression model, as this is the only way he or she can evaluate the regression model in scientific publications and thus correctly interpret their findings.