Irfan Ahmed, PhD

Data structure   Populations and samples A population is the entire collection of ‘things’ in which we are interested. A sample is a subset of a population. We wish to make an inference about a population of interest based on information obtained from a sample from that population. E XAMPLES : _ You measure the profit/loss of 50 public hospitals in Victoria, randomly selected. Population: Sample: Points of interest: _ Sales on 500 products from one company for the last 5 years are analysed. Population: Sample: Points of interest: Cases and variables Think about your data in terms of cases and variables . _ A case is the unit about which you are taking measurements. E.g., a person, a business. _ A variable is a measurement taken on each case. E.g., age, score on test, grade-level, income. Types of Data The ways of organizing, displaying and analysing data depends on the type of data we are investigating. _ Categorical Data (also called nominal or qualitative) e.g. sex, race, t...