Tratando Con Estadisticas

REVA BERMAN BROWN MARK SAUNDERS

Statistics

DEALING WITH

What you need to know

DEALING WITH STATISTICS: WHAT YOU NEED TO KNOW

DEALING WITH STATISTICS: WHAT YOU NEED TO KNOW

Reva Berman Brown and Mark Saunders

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 © Mark Saunders and Brandon Brown 2008 All rights reserved. Except for the quotation of short passages for the purpose of criticism and review, no part of this publication may 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-13: 978-0-33-521546-1(pb) 978-0-33-521547-8 (hb) ISBN-10: 0-33-522117-3 (pb) 0-33-522118-1 (hb) Library of Congress Cataloging-in-Publication Data CIP data applied for

Typeset by Kerrypress, Luton, Bedfordshire Printed in the UK by Bell and Bain Ltd, Glasgow

Contents

1 2 3 4 5 6 7 Appendix 1 Appendix 2 Appendix 3

Preface About the authors Why you need to use statistics in your research Understandingstatistical language Linking data collection with analysis Presenting data Describing data Inferring differences and relationships from data What next? Asking questions and types of data Useful statistical software An alphabet of statistics Glossary Index

vii xi 1 11 23 39 53 71 93 97 107 111 113 127

Preface

Read this bit. It will save you time because it explains the kind of book this isand, perhaps more importantly, the kind of book it isn’t, which will make it easier for you to decide whether you will benefit from reading it or whether you would get more out of doing something else instead. Right at the beginning, we want to make clear that this is not the book for you if you want to cover the world of statistics in a rigorous and exhaustive manner. The guiding principle of thisbook is the need to know. If you are unlikely to need a particular statistical method in order to analyse the data that you have collected for your project or dissertation, then you won’t find any mention of it here. There are enough books on statistics out there, which range from relatively simple introductions to advanced mathematical expositions. This one has a different purpose. Itconcentrates on what you need for success in your assignment, project or dissertation, and ignores the minor roads and byways that the person very interested in statistics would be pleased to travel. As the textbooks (which, strictly speaking, this isn’t) put it, by the end of this book, you will be able to choose and use an appropriate and effective statistical technique that will allow you to analyse yourdata and write about your results and findings convincingly. In a sense, this is the book that we wish we could have used during our own studies. We both spent far too long in a fog of not understanding which statistics to use, when we should be using them and why we should be using them. As a consequence, the book concentrates on particular statistical tests and the three Ws – which test, whenand why – and mainly ignores the details of how to calculate them, leaving this area for the books that not only explain the mathematics behind the techniques, but also how to use statistical software to analyse your data.

viii Dealing with Statistics

This is not the book for you if you want what any normal, self-respecting textbook currently supplies: self-check and review questions and...