Innovations in E-learning, instruction technology, assessment, and engineering education

226 Pages·2007·1.737 MB·English

by  Magued Iskander

E3
dr
id
t
io T H I R D E D I T I O N
n
tL
ee
sa
t
r
LEARNING TO USE STATISTICAL TESTS IN PSYCHOLOGY sn L e a r n i n g t o u s e

THIRD EDITION ii
nn
g
Praise for the first edition: p

st
“An excellent textbook which is well planned, well written, and pitched at the yo
correct level for psychology students. I would not hesitate to recommend Greene c s t a t i s t i c a l t e s t s
and d’Oliveira to all psychology students looking for an introductory text on hu
statistical methodology.” os
Bulletin of the British Psychological Society le
o
s
Learning to Use Statistical Tests in Psychologythird edition has been updated g
t
throughout. It continues to be a key text in helping students to understand and ya i n p s y c h o l o g y
conduct statistical tests in psychology without panic! It takes students from the t
most basic elements of statistics teaching them: i
s
t
• How psychologists plan experiments and statistical tests
i
• Which considerations must be made when planning experiments c
• How to analyze and comprehend test results a
l
Like the previous editions, this book provides students with a step-by-step guide
to the simplest non-parametric tests through to more complex analysis of
variance designs. There are clear summaries in progress boxesand questions for
the students to answer in order to be sure that they have understood what they
have read.
The new edition is divided into four sections and within this structure each test
covered is illustrated through a chapter of its own. The sections cover:
• The principles of psychological research and psychological statistics
• Statistical tests for experiments with two or three conditions G
• Statistical tests based on ANOVA (Analysis of Variance) conditions as well R
as tests for multiple comparisons between individual conditions
E
• Statistical tests to analyze relationships between variables
E
Presented in a student-friendly textbook format, Learning to Use Psychological N
Tests in Psychologyenables readers to select and use the most appropriate E
statistical tests to evaluate the significance of data obtained from psychological
experiments. A
N
Judith Greenewas educated at Oxford University and University
D
College London where she obtained her PhD in psychology. After ten years

lecturing at Birkbeck College London, she was appointed Professor of Psychology
D
at the Open University in 1976, where she is now Emeritus Professor.
’
O
Manuela d’Oliveiradid her first degree at Birkbeck College London
and obtained her PhD at the Open University, where she worked from 1976 to L
1985. She is now Invited Professor at the Faculty of Psychology and Educational I
V
Sciences, University of Porto, Portugal.
E
I
R
A
J U D I T H G R E E N E
M A N U E L A D ’ O L I V E I R A
Learning to use statistical
tests in psychology
THIRD EDITION

Learning to use statistical
tests in psychology
THIRD EDITION
Judith Greene
and
Manuela D’Oliveira

Open University Press
Open University Press
McGraw-Hill Education
McGraw-Hill House
Shoppenhangers Road
Maidenhead
Berkshire
England
SL6 2QL
email: [email protected]
world wide web: www.openup.co.uk
and Two Penn Plaza, New York, NY 10121-2289, USA
First published 1982
Reprinted 1983, 1985, 1987, 1988, 1989, 1990, 1992, 1993, 1994, 1995, 1996, 1998
First published in this second edition, 1999
Reprinted 2000, 2001
First published in this third edition, 2005
Copyright © Judith Greene and Manuela D’Oliveira, 2005
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 90 Tottenham Court
Road, London , W1T 4LP.
A catalogue record of this book is available from the British Library
ISBN-13: 978 0335 21680 3 (pb) 978 0335 21681 1 (hb)
ISBN-10: 0335 21680 3(pb) 0335 21681 1 (hb)
Library of Congress Cataloging-in-Publication Data
CIP data has been applied for
Typeset by RefineCatch Limited, Bungay, Suffolk
Printed in the UK by ???????????????????
To Norman, Kate and Matthew
and
To Pedro, Maria João, Catarina, Miguel, Mariana, Carolina

Contents
Preface to the third edition xii
Study guide for students xiv
Acknowledgements xvi
Part I Introduction 1
1 Research in psychology 3
1.1 Psychological research and statistics 3
1.2 Variability in human behaviour 3
1.3 Relationships between variables 4
1.4 Research hypothesis 4
1.5 Null hypothesis 4
1.6 Rationale for using statistical tests 5
1.7 Participants in psychological research 5

2 Experiments in psychology 7
2.1 The experimental method 7
2.2 Independent and dependent variables 7
2.3 Experimental and control conditions 8
2.4 Three or more experimental conditions 9
2.5 Same participants (related designs) 10
2.6 Different participants (unrelated designs) 10
3 Selecting statistical tests 12
3.1 Basic principles for selecting tests 12
3.2 Experiments 12
3.3 Number of experimental conditions 13
3.4 Related or unrelated designs 13
3.5 Non-parametric or parametric tests 13
3.6 Using the Decision Chart 13
viii Contents
4 Using statistical tests 15
4.1 Variability in data 15
4.2 Probabilities in statistical tables 17
4.3 Selecting a level of significance 17
4.4 One-tailed and two-tailed hypotheses 19
Part II Statistical tests for experiments 21
5 Introduction to non-parametric tests 23
5.1 Ordinal data 23
5.2 Assigning ranks to scores 23
5.3 Assigning tied ranks 24
5.4 Standard headings for presenting statistical tests 25
6 Wilcoxon test (related) 27
6.1 Scores from same participants 27
6.2 Ranking differences between conditions 28
6.3 Ranking plus and minus differences 29
6.4 Ties between scores 29
6.5 Selecting a statistical test in the Decision Chart 30
6.6 Using the Wilcoxon test (related) 31
7 Mann–Whitney test (unrelated) 36
7.1 Scores from different participants 36
7.2 Overall ranking of scores 37
7.3 Rank totals for each condition 37
7.4 Selecting a statistical test in the Decision Chart 38
7.5 Using the Mann–Whitney test (unrelated) 39
8 Introduction to parametric t tests 44
8.1 Comparisons between parametric and non-parametric tests 44
8.2 Numerical calculations for parametric tests 45

8.3 Calculating variances 46
8.4 Ratio of variances 46
9 t test (related) 48
9.1 Scores from same participants 48
9.2 Squaring differences 48
9.3 Ratio of variances 49
9.4 Selecting a statistical test in the Decision Chart 50
9.5 Using the t test (related) 50
10 t test (unrelated) 55
10.1 Scores from different participants 55
10.2 Squaring scores 55
10.3 Ratio of variances 56
10.4 Selecting a statistical test in the Decision Chart 57
10.5 Using the t test (related) 57
Contents ix
11 Friedman test (related) 62
11.1 Scores from same participants for three conditions 62
11.2 Ranking three conditions 63
11.3 Assigning tied ranks 64
11.4 Rank totals 65
11.5 Selecting a statistical test in the Decision Chart 66
11.6 Using the Friedman test (related) 66
12 Kruskal–Wallis test (unrelated) 72
12.1 Scores from different participants for three (or more)
conditions 72
12.2 Overall ranking of scores 73
12.3 Totals of ranks for each condition 74
12.4 Selecting a statistical test in the Decision Chart 75
12.5 Using the Kruskal–Wallis test (unrelated) 75
12.6 Note about names of non-parametric tests 79
Part III Analysis of variance 81
13 Introduction to ANOVA 83
13.1 Parametric tests 83
13.2 Analysis of variance 83
13.3 Sources of variance 84
13.4 Degrees of freedom 85
13.5 Requirements for parametric tests 86
13.6 Normal distribution 87
13.7 Computer statistical packages 88
14 One-way ANOVA (unrelated) 90
14.1 Scores from different participants 90
14.2 Definitions of variance 90

14.3 Selecting a statistical test in the Decision Chart 90
14.4 Using one-way ANOVA (unrelated) 91
15 One-way ANOVA (related) 96
15.1 Scores from same participant 96
15.2 Definitions of variance 96
15.3 Selecting a statistical test in the Decision Chart 97
15.4 Using one-way ANOVA (related) 97
16 Comparisons between ANOVA conditions 103
16.1 Overall differences in ANOVA 103
16.2 Graphs showing patterns of mean scores 103
16.3 Comparisons between individual conditions 104
16.4 Multiple comparisons between conditions 105
16.5 Using t tests for pairs of conditions 105
16.6 Adjusting significance levels 106