Introduction (1.1)

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
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
• 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
• 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 (SPSS, SAS,
Minitab, STATA, etc)
• Data must be entered into a data file:
– Rows typically represent individuals
– Columns typically represent variables