Introduction 1 1 Data Information collected by individuals

Introduction (1. 1) • Data - Information collected by individuals and/or organizations to gain knowledge regarding a field or question of interest. • Data Sources: – Surveys (Mail, Telephone, Internet) – Content Analysis (Newspaper, Magazine, Television) – Natural Experiments/Field Studies – Controlled Experiments • Statistics- Set of methods for collecting/analyzing data

Uses of Statistical Methods (1. 1) • Design - Planning/Implementing a study – Constructing a survey and deciding who to sample – Determining methods to be compared – Deciding which groups of units to be analyzed • Description - Summarizing data – Typical outcomes and distributions of outcomes – Tables and/or Graphs • Inference - Using sample data to predict or make statements regarding unobserved data

Description and Inference (1. 2) • Population - Full set of subjects of interest to researcher • Sample - Subset of population that is observed and measured in a data collection study • Descriptive Statistics - Summary of the information in a sample of data • Inferential Statistics - Statements regarding a population, based on a sample

Parameters and Statistics (1. 2) • Parameter - Numeric summary of a population – Population Mean - Average of a numeric measure – Population Proportion - Fraction having a particular characteristic • Statistic - Numeric summary of a sample • Populations can be well defined or conceptual • Inferences depend on the sample being representative of the general population

Statistical Computing (1. 3) • Statistical computer packages have become widespread over recent years, and their methods and ease of use have improved drastically in recent years (R, SPSS, SAS, Minitab, STATA, etc) • Data must be entered into a data file: – Rows typically represent individuals – Columns typically represent variables