This book is aimed at making the students learn 'Where and How' to apply the major statistical concepts and tools and finally Making Inferences or Decisions based on the available information (data). It emphasizes descriptive statistics and basics of probability theory that includes collection and organization of statistical data, frequency distributions, graphical presentation, measure of positions, measures of central tendency and dispersion as Descriptive Statistics, and sample spaces; events; probability measures; independent events; conditional probability; random variables, mean and variance of a random variable; binomial distribution; normal distribution as the Basics Of Probability Theory, as well as the Correlation and Regression Analysis. Risk factors which invlove in clinical trials and also graphical representation of data. As for as Statistical Inference is concerned clearly described Parametric and Non parametric tests including vital statistics and estimation of sample size also.