AN INTRODUCTION

FOR HEALTH AND SOCIAL SCIENCE

Pete Greasley

Quantitative Data Analysis Using SPSS

Quantitative Data Analysis Using SPSS

An Introduction for Health & Social Science

Pete Greasley

Open University Press McGraw-Hill Education McGraw-Hill House Shoppenhangers Road Maidenhead Berkshire England SL6 2QL email: enquiries@openup.co.uk world wide web: www.openup.co.uk and Two Penn Plaza, New York, NY 10121-2289, USA

First published 2008 Copyright © Pete Greasley 2008 All rights reserved. Except for the quotation of short passages for the purpose of criticism and review, no part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher or a licence from the Copyright Licensing Agency Limited. Details of such licences (for reprographic reproduction) may be obtained from the Copyright Licensing Agency Ltd of Saffron House, 6–10 Kirby Street, London EC1N 8TS. A catalogue record of this book is available from the British Library ISBN-10: 0 335 22305 2 (pb) 0 335 22306 0 (hb) ISBN-13: 978 0335 22305 3 (pb) 978 0335 22306 0 (hb) Library of Congress Cataloging-in-Publication Data CIP data applied for Typeset by ReﬁneCatch Limited, Bungay, Suffolk Printed in the UK by Bell and Bain Ltd, Glasgow

Contents

Introduction

1 5 5 7 7 13 16 17 18 19 19 20 21 22 25 27 28 31 33 33 38 41 41 45 46 50 52 56 57 58 58 60 61 61 61 63

1 A questionnaire and what to do with it: types of data and relevant analyses 1.1 The questionnaire 1.2 What types of analyses can we perform on this questionnaire? 1.2.1 Descriptive statistics 1.2.2 Relationships and differences in the data 1.3 Summary 1.4 Exercises 1.5 Notes

2 Coding the data for SPSS, setting up an SPSS database and entering the data 2.1 The dataset 2.2 Coding the data for SPSS 2.3 Setting up an SPSS database 2.3.1 Deﬁning the variables 2.3.2 Adding value labels 2.4 Entering the data 2.5 Exercises 2.6 Notes

3 Descriptive statistics: frequencies, measures of central tendency and illustrating the data using graphs 3.1 Frequencies 3.2 Measures of central tendency for interval variables 3.3 Using graphs to visually illustrate the data 3.3.1 Bar charts 3.3.2 Histograms 3.3.3 Editing a chart 3.3.4 Boxplots 3.3.5 Copying charts and tables into a Microsoft Word document 3.3.6 Navigating the Output Viewer 3.4 Summary 3.5 Ending the SPSS session 3.6 Exercises 3.7 Notes

4 Cross-tabulation and the chi-square statistic

4.1 Introduction 4.2 Cross-tabulating data in the questionnaire 4.3 The chi-square statistical test

vi

4.4 4.5 4.6 4.7 4.8

Quantitative Data Analysis Using SPSS

Levels of statistical signiﬁcance Re-coding interval variables into categorical variables Summary Exercises Notes 67 69 73 73 75 77 77 77 78 80 82 83 84 85 86 86 88 88 88 95 100 101 102 103 103 103 107 109 110 130 133 135

5 Correlation: examining relationships between interval data 5.1 Introduction 5.2 Examining correlations in the questionnaire 5.2.1 Producing a scatterplot in SPSS 5.2.2 The strength of a correlation 5.2.3 The coefﬁcient of determination 5.3 Summary 5.4 Exercises 5.5 Notes

6 Examining differences between two sets of scores

6.1 Introduction 6.2 Comparing satisfaction ratings for the two counsellors 6.2.1 Independent or related samples? 6.2.2 Parametric or non-parametric test? 6.3 Comparing the number of sessions for each counsellor 6.4 Summary 6.5 Exercises 6.6 Notes

7 Reporting the results and presenting the data

7.1 Introduction 7.2 Structuring the report 7.3 How not to present data Concluding remarks Answers to the quiz and exercises Glossary References Index

Introduction

I remember reading somewhere that for every mathematical formula, included in a book, the sales would be reduced by half. So guess what, there are no formulas, equations...