Includes bibliographical references and index.

This book is designed to give anyone who uses or develops tests a sound and up-to-date grasp of the principles of psychological assessment and to show how tests may best be used in practice. It is written for everyone who needs to understand use or develop psychological questionnaires, tests and assessments. Thus the likely readership will include students of psychology and other disciplines, test users and professionals - particularly those involved in personnel selection and placement.
Understanding these issues is important, as psychological tests are everywhere. Job applicants complete personality tests and have their cognitive abilities or leadership skills assessed. Health professionals use them to assess dementia and other clinical conditions. Children may be assessed for dyslexia, developmental difficulties or behavioural problems. Researchers in psychology, medicine, education and other disciplines routinely measure personality, cognitive abilities, attitudes, moods, emotional states and a whole host of other characteristics; whilst the rest of us read (and occasionally marvel at) these studies, we sometimes need to check whether their assessments and inferences are likely to be accurate. And we even complete tests and questionnaires in our spare time, to try to learn more about ourselves. But how can we decide which tests say something meaningful, and which are no more useful than reading tea leaves?
Psychometrics is a brave attempt to quantify all that is essentially human-our personality, mental abilities, moods and motives. What could be more important for the science and practice of psychology than that? Unusually, this book covers both the theory and practice of psychometric testing. The practical aspects include how to find (or construct) a test or questionnaire, put it on the internet, check the quality of the data, score it, and interpret the scores. The book also explains modern approaches to reliability theory, factor analysis, item response theory, network analysis and other key methodologies, and shows how tests and questionnaires may be validated. It also considers (and attempts to evaluate) some devastating criticisms of the whole rationale of psychological assessment made by Joel Michell and others.
What makes this book unique is its "hands-on" approach. Rather than showing equations (which experience tells me 9 of 10 students will ignore), most chapters are accompanied by some simple-to-use spreadsheets for Open Office and MicrosoftExcel. They have three purposes. Some of them show how commonly used techniques work; the spreadsheet which performs VARIMAX factor rotation in factor analysis,forexample. Some use simulated data to demonstrate an important point-for example,to show how test length influences relability. And some of the spreadsheets areutilities; they compute statistics and perform analyses which most statistical packagesignore. Thus one spreadsheet computes a whole range of different types of correlations between dichotomous (two-valued) variables. Another scores questionnaires. A third performs item analysis to identify and remove underperforming items. All the spreadsheets are integrated into the text in the form of exercises with clear instructions and learning outcomes.
Having read this book and worked through the exercises, students and researchers should have a sound grasp of the principles of modern psychological assessment methods. They should be able to find tests and questionnaires, administer and score them, analyse their psychometric properties and interpret their meaning- whilst being alert to the strengths and weaknesses of questionnaires, tests and rating scales. They should also be able to design and validate a scale or test measuring personality mood or some cognitive ability. That is my hope, anyway.
Thanks are due to several people. Several generations of undergraduate and graduate students at Queen's University, Belfast, taught me how to teach psychometrics whilstI was trying to teach them psychometrics, and thanks are also due to Adam Woods at Routledge, and to Scott Coello for the cover.
And of course, special thanks to Wesley-for his unflagging support, love and help -aided and abetted by Lucky and PussPuss. -- Preface