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Chapter

11

Part 3

Measurement Concepts

MEASUREMENT

LEARNING OBJECTIVESLEARNING OBJECTIVESLEARNING OBJECTIVESLEARNING OBJECTIVES

1. To know how a researcher might answer the question “What is to be measured?”

2. To define the term operational definition

3. To distinguish among nominal, ordinal, interval, and ratio scales

4. To understand the need for index or composite measures

5. To define the three criteria for good measurement

6. To discuss the various methods for determining reliability

7. To discuss the various methods for assessing validity

What you will learn in this chapter

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• A precise definition of the concept may require A precise definition of the concept may require a description of how it will be measureda description of how it will be measured

• Frequently there is more than one way to Frequently there is more than one way to measure a particular conceptmeasure a particular concept

• True measurement of concepts requires a True measurement of concepts requires a process of assigning scores or numbers to the process of assigning scores or numbers to the attributes of people or objects.attributes of people or objects.

• The question becomes “On what basis will The question becomes “On what basis will numbers or scores be assigned to the numbers or scores be assigned to the concept?”concept?”

What Is To Be Measured?What Is To Be Measured?What Is To Be Measured?What Is To Be Measured?

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• ConceptsConceptsA generalized idea about a class of objects,

attributes, occurrences, or processes

• Operational DefinitionsOperational DefinitionsAn explanation that gives meaning to a concept by

specifying the activities or operations necessary to measure it

Conceptual definition A verbal explanation of the meaning of a concept. It defines

what the concept is and what it is not

What Is To Be Measured? (cont’d)What Is To Be Measured? (cont’d)What Is To Be Measured? (cont’d)What Is To Be Measured? (cont’d)

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• Measurement RuleMeasurement Rule Example: “Assign the numerals 1 through 7 to

individuals according to how brand loyal they are. If the individual is extremely brand loyal, assign a 7. If the individual is a total brand switcher with no brand loyalty, assign the numeral 1.”

Rules of MeasurementRules of MeasurementRules of MeasurementRules of Measurement

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• ScaleScaleAny series of items that are arranged progressively

according to value or magnitude; a series into which an item can be placed according to its quantification

• Nominal ScaleNominal ScaleA scale in which the numbers or letters assigned to

objects serve as labels for identification or classification

• Ordinal ScaleOrdinal ScaleA scale that arranges objects or alternatives

according to their magnitude in an ordered relationship

Types of ScalesTypes of ScalesTypes of ScalesTypes of Scales

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• Interval ScaleInterval ScaleA scale that both arranges objects according to their

magnitudes and distinguishes this ordered arrangement in units of equal intervals

• Ratio ScaleRatio ScaleA scale that has absolute rather than relative

quantities and an absolute zero where there is an absence of a given attribute

Types of Scales (cont’d)Types of Scales (cont’d)Types of Scales (cont’d)Types of Scales (cont’d)

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• Mathematical and Statistical Analysis of ScalesMathematical and Statistical Analysis of Scales

Types of Scales (cont’d)Types of Scales (cont’d)Types of Scales (cont’d)Types of Scales (cont’d)

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Type of Scale Numerical Operations Descriptive Statistics . Nominal Counting Frequency in each category

Percentage in each category Mode

Ordinal Rank Ordering Median Range Percentile ranking

Interval Arithmetic operations Mean that preserve order and Standard deviation relative magnitudes Variance

Ratio Arithmetic operations Geometric mean on actual quantities Coefficient of variation

Attribute A single characteristic or fundamental feature of an object,

person, situation, or issue

Index (or composite) measure A composite measure of several variables used to measure

a single concept; a multi-item instrument

Index MeasuresIndex MeasuresIndex MeasuresIndex Measures

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• ReliabilityReliabilityThe degree to which measures are free from random

error and therefore yield consistent resultsTest-retest method

Administering the same scale or measure to the same respondents at two separate points in time to test for stability

Split-half method A method for assessing internal consistency by checking

the results of one-half of a set of scaled items against the results from the other half

Three Criteria For Good MeasurementThree Criteria For Good MeasurementThree Criteria For Good MeasurementThree Criteria For Good Measurement

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• Reliability (cont’d)Reliability (cont’d)Equivalent-form method

A method that measures the correlation between alternative instruments, designed to be as equivalent as possible, administered to the same group of subjects

Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)

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• ValidityValidityThe ability of a scale to measure what was intended

to be measuredEstablishing validity

Face (or content) validity: Professional agreement that a scale’s content logically appears to accurately reflect what was intended to be measured

Criterion validity: The ability of a measure to correlate with other standard measures of the same construct or established criterion

Construct validity: The ability of a measure to provide empirical evidence consistent with a theory based on the concepts

Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)

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• Reliability versus ValidityReliability versus Validity– Reliability, although necessary for validity, is not

sufficient by itself Example: Exhibit 11.5

Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)

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• SensitivitySensitivityA measurement instrument’s ability to accurately

measure variability in stimuli or responses

Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)Three Criteria For Good Measurement (cont’d)

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