Statistics are needed at every step of a scientific analysis. Statistics allow us to make decisions, evaluate observations, models, formulate questions and proceed forward with further investigations. The main goal of X-ray data analysis is to learn more about the physical properties of a source. When the new data arrives, statistics are employed to quantify the measurements. Typically, a parameterized approach to model the data is taken wherein physical models with certain parameters (e.g. temperature and density of a hot medium emitting X-rays) are applied to the data. Finding and evaluating a model that best describes the observed data will be the focus of my talk.