# STAB22H3 Lecture Notes - Lecture 1: Statistical Inference, Categorical Variable, Observational Study

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## Document Summary

Statistics is the science of collecting, organizing and interpreting data. The goal of statistics is to gain information and understanding from data. Statistical inference is making a decision or a conclusion based on the data. Data are numerical facts with context and we need to understand the context if we are to make sense of the numbers. Individuals are the objects upon which we collect data. Individuals can be people, animals, and many other things. A variable is any characteristic of an individual. A variable can take different values for different individuals. Categorical variable: a variable that places an individual into one of two or more groups or categories. Quantitative variable: a variable that takes numerical values for which arithmetic operations such as adding and averaging make sense. The distribution of a variable tells us what values it takes and how often it takes these values. Ex: flip a coin once and let x = # of heads.