Chapter 2 Introduction to Measurement and Statistics
Chapter 2 Introduction to Measurement and Statistics The Measurement Processes
Accuracy Validity
Reliability
The Process of Measurement measurement: process of assigning a symbol (usually a numeral) according to a set of rules to reflect the amount of a characteristic something (usually a person or animal) possesses • may involve categorizing events (qualitative) • may involve using numbers to characterize the amount (quantitative)
The Process of Measurement
Four steps: 1. Identification & definition of object or concept to be measured. 2. Identification & definition of standard to which object will be compared. 3. Comparison between object & standard. 4. Quantitative statement is made of the relationship between the object or concept & standard.
Levels of Measurement nominal scale: scale which groups subjects into mutually exclusive categories • example: occupation • sales, teacher, lawyer, doctor, other • frequency data: grouping and counting of categories • 12 salespeople, 10 teachers, 5 lawyers, 3 doctors, 6 other
Levels of Measurement ordinal scale (rank order scale): provides quantitative order to the variables, but does not indicate how much better one score is than another • example: small, medium, and large drinks at a restaurant interval scale: scale has equal units of measurement but without an absolute zero point • example: temperature in Fahrenheit • Scores on examinations ratio scale: most complete scale of measurement; based on order, has equal units of measurement, and uses zero to represent the absence of value • example: distance Notice that the higher levels of measurement contain all the characteristics of those that fall below them.
Accuracy Validity
Reliability
The Process of Measurement measurement: process of assigning a symbol (usually a numeral) according to a set of rules to reflect the amount of a characteristic something (usually a person or animal) possesses • may involve categorizing events (qualitative) • may involve using numbers to characterize the amount (quantitative)
The Process of Measurement
Four steps: 1. Identification & definition of object or concept to be measured. 2. Identification & definition of standard to which object will be compared. 3. Comparison between object & standard. 4. Quantitative statement is made of the relationship between the object or concept & standard.
Levels of Measurement nominal scale: scale which groups subjects into mutually exclusive categories • example: occupation • sales, teacher, lawyer, doctor, other • frequency data: grouping and counting of categories • 12 salespeople, 10 teachers, 5 lawyers, 3 doctors, 6 other
Levels of Measurement ordinal scale (rank order scale): provides quantitative order to the variables, but does not indicate how much better one score is than another • example: small, medium, and large drinks at a restaurant interval scale: scale has equal units of measurement but without an absolute zero point • example: temperature in Fahrenheit • Scores on examinations ratio scale: most complete scale of measurement; based on order, has equal units of measurement, and uses zero to represent the absence of value • example: distance Notice that the higher levels of measurement contain all the characteristics of those that fall below them.
