Introduction to Statistics

This module is an introduction to the science of statistics.

Statistics is the science of collecting, organising, summarising, analyzing, and interpreting data. Descriptive statistics refers to summarising data with numbers or pictures while inferential statistics is about making conclusions or decisions based on data.

The goal of statistics is to use imperfect information (our data) in order to infer facts, make decisions, and make predictions about the world.

A statistic is a number or value measured within some particular context.

It is essential to understand the context:

• Which data were collected?
• How and why were the data collected?
• On which individuals or entities were the data collected?
• What questions do we hope to answer from the data?

In the material that follows, we’ll examine several summary statistics and plots useful for taking an initial look at the data and what we can learn from them. We’ll consider how to describe the centre, spread, and shape of numerical variables, and deviations from the overall pattern. For categorical variables, we’ll see how we can summarize the size of the membership in each group using tables, pie charts, and bar charts.