STATISTICS FOR THE LIFE SCIENCES 4TH EDITION

STATISTICS FOR THE LIFE SCIENCES Fourth Edition Myra L. Samuels Purdue University Jeffrey A. Witmer Oberlin College Andrew A. Schaffner California Polytechnic State University, San Luis Obispo Prentice Hall Boston Columbus Indianapolis New York San Francisco Upper Saddle River Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montréal Toronto Delhi Mexico City São Paulo Sydney Hong Kong Seoul Singapore Taipei TokyoEditor-in-Chief: Deirdre Lynch Acquisitions Editor: Christopher Cummings Senior Content Editor: Joanne Dill Associate Editor: Christina Lepre Senior Managing Editor: Karen Wernholm Production Project Manager: Patty Bergin Digital Assets Manager: Marianne Groth Production Coordinator: Katherine Roz Associate Media Producer: Nathaniel Koven Marketing Manager: Alex Gay Marketing Assistant: Kathleen DeChavez Senior Author Support/Technology Specialist: Joe Vetere Permissions Project Supervisor: Michael Joyce Senior Manufacturing Buyer: Carol Melville Design Manager: Andrea Nix Cover Designer: Christina Gleason Interior Designer: Tamara Newnam Production Management/Composition: Prepare Art Studio: Laserwords Cover image: © Rudchenko Liliia/Shutterstock Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and Pearson Education was aware of a trademark claim, the designations have been printed in initial caps or all caps. Library of Congress Cataloging-in-Publication Data Samuels, Myra L. Statistics for the life sciences / Myra Samuels, Jeffrey Witmer. -- 4th ed. / Andrew Schaffner. p. cm. Includes bibliographical references and index. ISBN 978-0-321-65280-5 1. Biometry--Textbooks. 2. Medical statistics--Textbooks. 3. Agriculture--Statistics--Textbooks. I. Witmer, Jeffrey A. II. Schaffner, Andrew. III. Title. QH323.5.S23 2012 570.1'5195--dc22 Copyright: © 2012, 2003, 1999 Pearson Education, Inc. All rights reserved. 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. Printed in the United States of America. For information on obtaining permission for use of material in this work, please submit a written request to Pearson Education, Inc., Rights and Contracts Department, 501 Boylston Street, Suite 900, Boston, MA 02116, fax your request to 617-671-3447, or e-mail at 1 2 3 4 5 6 7 8 9 10—EB— ISBN-10: ISBN-13: 978-0-321-65280-5Preface vii 1 INTRODUCTION 1 1.1 Statistics and the Life Sciences 1 1.2 Types of Evidence 7 1.3 Random Sampling 15 2 DESCRIPTION OF SAMPLES AND POPULATIONS 26 2.1 Introduction 26 2.2 Frequency Distributions 28 2.3 Descriptive Statistics: Measures of Center 40 2.4 Boxplots 45 2.5 Relationships between Variables 52 2.6 Measures of Dispersion 59 2.7 Effect of Transformation of Variables (Optional) 68 2.8 Statistical Inference 73 2.9 Perspective 79 3 PROBABILITY AND THE BINOMIAL DISTRIBUTION 84 3.1 Probability and the Life Sciences 84 3.2 Introduction to Probability 84 3.3 Probability Rules (Optional) 94 3.4 Density Curves 99 3.5 Random Variables 102 3.6 The Binomial Distribution 107 3.7 Fitting a Binomial Distribution to Data (Optional) 116 4 THE NORMAL DISTRIBUTION 121 4.1 Introduction 121 4.2 The Normal Curves 123 4.3 Areas Under a Normal Curve 125 4.4 Assessing Normality 132 4.5 Perspective 142 CONTENTS iii5 SAMPLING DISTRIBUTIONS 145 5.1 Basic Ideas 145 5.2 The Sample Mean 149 5.3 Illustration of the Central Limit Theorem (Optional) 159 5.4 The Normal Approximation to the Binomial Distribution (Optional) 162 5.5 Perspective 167 6 CONFIDENCE INTERVALS 170 6.1 Statistical Estimation 170 6.2 Standard Error of the Mean 171 6.3 Confidence Interval for μ 177 6.4 Planning a Study to Estimate μ 187 6.5 Conditions for Validity of Estimation Methods 190 6.6 Comparing Two Means 199 6.7 Confidence Interval for 206 6.8 Perspective and Summary 212 7 COMPARISON OF TWO INDEPENDENT SAMPLES 218 7.1 Hypothesis Testing: The Randomization Test 218 7.2 Hypothesis Testing: The t Test 223 7.3 Further Discussion of the t Test 234 7.4 Association and Causation 242 7.5 One-Tailed t Tests 250 7.6 More on Interpretation of Statistical Significance 260 7.7 Planning for Adequate Power (Optional) 267 7.8 Student’s t: Conditions and Summary 273 7.9 More on Principles of Testing Hypotheses 277 7.10 The Wilcoxon-Mann-Whitney Test 282 7.11 Perspective 291 8 COMPARISON OF PAIRED SAMPLES 299 8.1 Introduction 299 8.2 The Paired-Sample t Test and Confidence Interval 300 8.3 The Paired Design 310