Introduction to statistical methodology: statistics a science that deals with collecting data, describing/summarizing the data, comparing groups, fitting models, & making predictions. Sources of data: primary data collected by the experimenters themselves, experimental data data from random experiments, observational data data collected without experimental setup, secondary data data collected from secondary source. Statistical science encompasses a body of methods for obtaining & analyzing data. The methods can be divided into 3 groups: design. Deals with planning how to gather informative data for a research study to investigate questions of interest to us. It enables social scientists to select people to interview & construct the questionnaire to administer: description. Social scientists often us graphs & tables for this purpose. The purpose is to reduce the data to a simpler & more understandable form without distorting or losing much information: inference. Making statement about some characteristics of the study population by analyzing uncertainty in an objective manner.