Measurement in Health Behavior

Measurement in Health Behavior offers faculty, students, researchers, and public health professionals the information they need to improve their knowledge of instrument development and testing and their understanding of reliability and validity testing discussed in articles and reports. The book also helps improve students’ and professionals’ ability to conduct basic tests for reliability and validity and hones their skills in interpreting the results of data analysis. Based on data collected from the author’s more than ten years of research and program development, Measurement in Health Behavior provides realistic examples from the public health arena to clearly demonstrate the book’s concepts.

Tables, Figures, and Exhibits xv

Preface xxi

The Author xxv

1 Introduction to Measurement 1

Role of Measurement in Health Education and Health Behavior Research 1

Brief History of Psychosocial Measurement 3

Conceptualization of Measurement 6

Reasons for Measuring Concepts 8

Scales of Measurement 9

Nominal Scale 9

Ordinal Scale 11

Interval Scale 12

Ratio Scale 14

Levels of Measurement and Statistics 15

Major Concepts of Measurement: Reliability and Validity 16

Reliability 16

Validity 17

Summary 17

2 Types of Measures 18

Self-Report 19

Interviews 19

Questionnaires 20

Journals and Diaries 22

Response Scales 23

Scaling Methods 24

Visual Analog Scale 24

Thurstone Scale 26

Likert Scale 28

Guttman Scale 29

Semantic Differential Rating Scale 30

Indexes 31

Observations 33

Biobehavioral Measures 33

Electronic Measures 34

Summary 35

3 Measurement Error 36

Definition 37

Classification of Measurement Error 38

Random Error 38

Systematic Error 39

Measurement Error Factors 40

Respondent Factors 40

Response Sets 42

Social Desirability 42

Acquiescence and Nay-Saying 44

End Aversion (Central Tendency) 44

Positive Skew 45

Halo 46

Recall 46

Instrument Factors 48

Strategies to Reduce Errors on Self-Report Questionnaires 50

Strategies to Reduce Errors During Interviews 51

Situational Factors 51

Measurement Rules 53

Summary 53

4 Survey Development 54

Definition 55

Basic Principles of Survey Construction 55

Purpose 55

Objectives 56

Respondents 59

General Principles of Item Writing 59

The Do’s of Item Writing 60

The Don’ts of Item Writing 68

Survey Format 70

Survey Administration 72

Summary 74

5 Knowledge Tests 75

Test Construction 76

State the Purpose of the Test 76

State the Test Objectives 78

Review Content 79

Develop a Table of Test Specifications 79

Domain-Sampling Model 80

Types of Items 84

Multiple-Choice Items 85

True/False Items 90

Item Analysis 92

Item-Objective Congruency 92

Average Congruency Percentage 98

Difficulty Index 98

Item Discrimination Index 101

Summary 101

6 Theory and Measurement 103

Linking Measurement to Theory-Based Health Practice and Research 104

Gibbs’s Model 106

Theoretical and Operational Definitions 109

Conceptualization Issues in Scale Development 110

Survey Versus Scale 110

Single-Item Versus Multiple-Item Scales 111

Concept Selection 113

Concept Analysis 114

Identify Definitions and Uses of the Concept 114

Identify Critical Attributes of the Concept 116

Identify Dimensions of the Concept 117

Identify Similar and Different Concepts 117

Identify Antecedents and Consequences of the Concept 118

Write a Model Case 118

State the Variables 119

Summary 119

7 Item Writing and Scaling 121

Item Development Process 122

State the Theoretical Definition 123

Identify Dimensions of the Concept 123

Create a Content-Domain by Concept-Dimension Matrix 123

Decide How Many Items to Include for Each Matrix Cell 124

Write Items for Each Content-Domain by Concept-Dimension Cell 126

Literature Review 126

Qualitative Interviews 126

Other Instruments 127

Write Rules for Scale Scoring and Administration 128

Summated Rating Scales 128

Types of Response Options 128

Number of Response Options 130

Odd or Even Number of Categories 131

Meanings of Response Option Adjectives or Adverbs 132

Use of Adjectives, Adverbs, or Numbers, or Combinations Thereof 132

Positively and Negatively Worded Items 133

Scoring 133

Summary 135

8 Review of Statistical Concepts 136

Basic Statistical Concepts 137

Frequency Distribution 137

Measures of Central Tendency 139

Measures of Dispersion 139

SPSS Commands 140

Recode Negatively Worded Items Using SPSS 144

Compute Total Scale Scores Using SPSS 145

Review of Correlation 146

Interpretation of the Correlation Coefficient 150

Correlation Matrix 152

Correlation Issues 152

Causality 152

Sample Size 153

Group Differences 154

Restriction of Range 154

Variance 154

Reporting Results of Correlation Analysis 156

Analysis of Variance 157

Definition and Use 157

SPSS Commands for a One-Way ANOVA 158

Interpreting a One-Way ANOVA 158

Summary 162

9 Fundamentals of Reliability 163

Classical Test Theory 165

Observed, True, and Error Scores 165

Assumptions and Characteristics 167

Reliability Coefficient 170

Estimate of Reliability 172

Calculation of Variance Due to the True Score 173

Calculation of the Reliability Index 174

Summary 174

10 Reliability Assessment and Item Analysis 176

Methods of Reliability Assessment 177

Equivalence 177

Stability 178

Internal Consistency 181

Split-Half 181

Coefficient Alpha 184

Cronbach’s Alpha 186

Kuder-Richardson Formula 20 189

Factors Associated with Coefficient Alpha 191

Test Length and Interitem Correlation 191

Test Adjustments to Increase Alpha 191

Standards of Reliability 193

Item Analysis 193

Intrarater and Interrater Reliability 199

Intraclass Correlation Coefficient 203

Standard Error of Measurement 205

Generalizability Theory 206

Summary 210

11 Validity 211

Test Content 214

Procedures 215

Content Validity Index 218

Face Validity 219

Response Processes 220

Procedures 221

Think Aloud 221

Verbal Probe 222

Evaluation 222

Relationships to Other Variables 224

Criterion Validity 225

Construct Validity 229

Multitrait-Multimethod Matrix 233

Validity Issues 235

Summary 236

12 Factor Analysis 237

Exploratory Factor Analysis 238

Definition 238

Conceptual Basis 241

How Factor Analysis Works 244

Steps in Factor Analysis 244

Basic Requirements for FA 246

Initial Assessment 247

Evaluation of the Matrix 248

Evaluation of the Determinant 250

Test for an Identity Matrix 251

Tests of Sampling Adequacy 252

Selection of the Type of Factor Analysis 253

Initial Extraction 255

Eigenvalues 256

Communality 257

Number of Factors 261

Rotation of Factors 263

Interpretation of Factors 267

Confirmatory Factor Analysis 273

Summary 275

13 Item Response Theory 276

Disadvantages of Classical Test Theory 277

Item Response Theory Basics 278

Polytomous Models 285

Technical Issues 288

Summary 289

References 290

Index 297

Colleen Konicki Di Iorio, Ph.D., R.N., F.A.A.N, is a professor in the department of behavioral sciences and health education at Rollins School of Public Health, Emory University, and the associate editor of The Journal of Nursing Measurement. She has published numerous journal articles and book chapters on research and measurement methods in public health. Di Iorio is a contributor to the third edition of Health Education and Health Behavior from Jossey-Bass. Measurement in Health Behavior

Measurement in Health Behavior is a practical, step-by-step introduction to the wide variety of measurement methods in the field of health behavior research. The text addresses the practical issues related to the development of measures of health behavior and provides information on how to conduct the reliability and validity tests.

Measurement in Health Behavior offers faculty, students, researchers, and public health professionals the information they need to improve their knowledge of instrument development and testing and their understanding of reliability and validity testing discussed in articles and reports. The book also helps improve students' and professionals' ability to conduct basic tests for reliability and validity and hones their skills in interpreting the results of data analysis. Based on data collected from the author's more than ten years of research and program development, Measurement in Health Behavior provides realistic examples from the public health arena to clearly demonstrate the book's concepts.

A comprehensive resource, Measurement in Health Behavior

• Presents a brief description of the different types of measures that are used to collect data about health behavior or associated factors
• Includes strategies for reducing measurement errors
• Offers information about survey development and knowledge test construction
• Covers information about scale development and includes important information related to the analysis of concepts
• Presents basic statistical concepts and puts the focus on reliability
• Offers a presentation of classical test theory and includes the different types of reliability assessment
• Includes several strategies for assessing validity and presents the basic principles of factor analysis
• Contains an elementary description of item response theory