This chapter provides an introduction to several fundamental methods for analyzing data from clinical trials, including an overview of two very important and related concepts: confidence intervals and tests of hypotheses. In making statistical inference, one draws a sample from a population and computes one or more statistics. Most confidence intervals use similar methods. In general, a confidence interval is made up of a point estimate, the standard error of that estimate, and a tabular value. The method of intention to treat has become the standard for analyzing data from clinical trials. Regulatory organizations such as FDA and the International Conference on Harmonisation (ICH) recommend that the primary efficacy analysis be based on the intention to treat principle. Multiple methods have been used to impute missing data. A method that was very commonly used in the past is called 'last observation carried forward' (LOCF).