Scale Development: Theory and Applications

This book is a great introduction to psychometrics. If you knowledge of scale creation is somewhere between nothing and a moderate amount, then this book is for you. The book contains many helpful hints (such as how to generate questions/items) and helps make sure that you have a solid psychometrics foundation. So, make sure that you read it before you create your scale and pilot test it. However, the book does not always give a ton of details. This can be both positive and negative. It is more of an outline about what to do than a detailed step-by-step guide. For instance, it explains how reliability is calculated for a 5-point scale (e.g., strongly disagree, disagree, neutral, agree, strongly agree) but it does not explain how reliability is calculated for a dichotomous scale (e.g., true, false). Other times, though, it gives solid details (e.g., your scale's pilot test should contain 3-4 times the number of items you want your final scale to have). Nevertheless, if you need to brush up on scale creation concepts, you can read this entire book in a weekend and be in good shape. If you have ever taken an introduction to statistics course, then you will not be overwhelmed by the statistics in this book as the book is much more conceptual than technical. I'd recommend that you buy it and keep it on your shelf as a quick reference guide. I plan on referring back to it frequently, but I also plan on buying a more detailed psychometrics book.

My colleague Doug recently completed a research study on the level of engagement in the Federal workforce. He used data from a 2005 governmentwide survey of nearly 37,000 Federal employees. Although Doug has a solid background in Federal employment issues like employee engagement, this was the first time he used a group of survey questions to create and analyze a measurement scale. This book is one of the resources Doug used to make his project a success. Robert DeVellis's book covers the fundamentals of social science scale development in a straightforward manner. This book explains basic measurement concepts clearly and contains sufficient practical guidance to support construction of a working scale. The reader will need to obtain access to a statistical program and instruction in its use from another source. Chapter 1 briefly reviews the history of social science measurement, including the role played by statistics and psychophysics. A discussion of the relationship between theory and measurement includes the risks of careless measurement practice. It ends on page 13 with a useful one-paragraph preview of the remaining seven chapters. Chapter 2 defines the relationship between constructs and the measures that allow us to observe them. It introduces path diagrams and outlines the assumptions of classical measurement theory. Chapter 3 defines measurement reliability and introduces coefficient alpha as a measure of the internal consistency of a scale. More advanced reliability topics are outlined with some reference to formulas and covariance matrices. The next two chapters are the book's core. Chapter 4 defines content, criterion-related, construct and face validity and distinguishes between validity and accuracy. The discussion of validity coefficients and multi-method multi-trait approaches to studying validity equip the reader to understand validity studies in the measurement literature. Chapter 5 lays out an eight-step process for developing a scale of questions to measure some construct of the reader's choice. These steps are (slightly reworded): - 1. Define clearly what you want to measure. - 2. Create a set of draft questions. - 3. Select a common format and set of answer options for the questions. - 4. Have experts review and revise the questions. - 5. Consider using "social desirability" or similar questions. - 6. Field test the questions with "real people." - 7. Analyze the results of your field test. - 8. Decide how many questions--and which questions--to keep. The real value in this book is the practical guidance given for each of these steps. There is enough here to get you through your first project, but not so much that it overwhelms. Chapter 6 introduces factor analysis as a statistical procedure that helps scale developers understand how their scale works, particularly if there are two or three different things that the scale is measuring. The author does an excellent job explaining the concepts o

This short volume is an excellent overview of how to create scales and indexes from survey items. The author assumes familiarity with the concepts behind reliability and validity, so the book is best used a supplement to an already developed measurement foundation. I highly recommend adding this to your reference library, I am sure you will refer to it throughout your career.

If you've never developed scales for survey research before, this is probably one of the most readable and actionable books describing the process step by step. Browse through it in your local library before you buy a copy. Highly recommended.

It's a worth reading for those who wishes to know more about scale development. Chapters on "Reliability" and "Validity" are a bit too brief, I dare say. On the other hand, Chapter 5 provides really easy to follow, step by step instructions in building a scale. Readers following through these instructions shouldn't find difficulty constucting their own scales! Perhaps, for those who wishes to know more about issues concerning scale reliability and validity, they may refer to Spector's "Summated Rating Scale Construction (A Sage publication).