Basic Statistics 1

Measurement

-- Professor Stipak presents --

Simple Statistics Example

• How do we report motor vehicle theft rates?

Simple Statistics Example

• How do we report motor vehicle theft rates?

• Accepted practice: Thefts per 1000 population

• Alternative: Thefts per 1000 motor vehicles

Motor Vehicle Theft Rates:Thefts / 1000 Population

New York City 12

Chicago 16

Philadelphia 19

Los Angeles 20

Detroit 22

Motor Vehicle Theft Rates:Thefts / 1000 Motor Vehicles

Los Angeles 34

Chicago 45

Detroit 47

Philadelphia 49

New York City 53

Measurement: Importance

Measurement

Data

Statistics

Measurement: Overview

• Basic Concepts

• Levels of Measurement

• Validity/Reliability

Measurement: Basic Concepts

• UOA / Case

• Variable

• Value– Record data in a table: rows-cases, cols-variables

Measurement: Levels

• Ratio

• Interval

• Ordinal

• Nominal

Data In Public Agencies

• Types of data in agencies

• Sources of data

• Types of datasets, examples: census data, merged data

Measurement: Quality

• Reliability of Measurement

• Validity of Measurement

• Measurement Error