STATISTICAL APPLICATIONS for. HEALTH INFORMATION MANAGEMENT Second Edition

Transcription

1 1290.ChFM 4/21/05 12:59 PM Page i STATISTICAL APPLICATIONS for HEALTH INFORMATION MANAGEMENT Second Edition CAROL E. OSBORN, PhD, RHIA The Ohio State University Health System Assistant Director Documentation and Compliance Department of Medical Information Management

2 1290.ChFM 4/21/05 12:59 PM Page ii World Headquarters Jones and Bartlett Publishers 40 Tall Pine Drive Sudbury, MA Jones and Bartlett Publishers Canada 2406 Nikanna Road Mississauga, ON L5C 2W6 CANADA Jones and Bartlett Publishers International Barb House, Barb Mews London W6 7PA UK Jones and Bartlett s books and products are available through most bookstores and online booksellers. To contact Jones and Bartlett Publishers directly, call , fax , or visit our website Substantial discounts on bulk quantities of Jones and Bartlett s publications are available to corporations, professional associations, and other qualified organizations. For details and specific discount information, contact the special sales department at Jones and Bartlett via the above contact information or send an to specialsales@jbpub.com. Copyright 2006 by Jones and Bartlett Publishers, Inc. Cover image: Photos.com All rights reserved. No part of the material protected by this copyright notice may be reproduced or utilized in any form, electronic or mechanical, including photocopying, recording, or any information storage or retrieval system, without written permission from the copyright owner. Library of Congress Cataloging-in-Publication Data Osborn, Carol E. Statistical applications for health information management / Carol E. Osborn. 2nd ed. p. ; cm. Includes bibliographical references and index. ISBN X (pbk.) 1. Medical statistics. 2. Health services administration Statistical methods. [DNLM: 1. Biometry methods. 2. Data Interpretation, Statistical. 3. Health Services Administration. 4. Research methods. WA 950 O815s 2005] I. Title. RA409.O dc Production Credits Publisher: Michael Brown Editorial Assistant: Kylah Goodfellow McNeill Production Director: Amy Rose Associate Production Editor: Renée Sekerak Production Assistant: Rachel Rossi Senior Marketing Manager: Ed McKenna Associate Marketing Manager: Marissa Hederson Manufacturing Buyer: Therese Bräuer Composition: ATLIS Graphics Cover Design: Timothy Dziewit Printing and Binding: Malloy Incorporated Cover Printing: Malloy Incorporated Printed in the United States of America

3 1290.ChFM 4/21/05 12:59 PM Page iii CHAPTER 1 About the Author Carol E. Osborn, PhD, RHIA, earned an undergraduate degree in health information management from Mercy College of Detroit, a master s degree in health sciences education and evaluation from the State University of New York at Buffalo, and a PhD in research and evaluation from The Ohio State University. Dr. Osborn has spent most of her career in the academic setting, teaching at both the University of Illinois at Chicago and at The Ohio State University. She is currently Assistant Director, Medical Information Management, The Ohio State University Health System. She has also consulted in a variety of health care settings including acute care, specialty care, and healthcare-related organizations. She has served on The Ohio State University s Institutional Review Board for over 10 years. She was part of the allied health education consulting team to the Ministry of Health, Saudi Arabia. She has also served as a consultant to HIM baccalaureate degree programs. Dr. Osborn has been active in professional associations at the state and national levels. She served as secretary, treasurer, and president of the Illinois Medical Record Association. Nationally she has served on the Council of Education, Sub-Panel for Accreditation of Academic Programs, and the Joint Committee on Education, and for 10 years, as a member of the Panel of Accreditation Surveyors. She has authored numerous articles and book chapters for professional journals and textbooks, and she is currently on the editorial review board for Perspectives in Health Information Management. iii

4 1290.ChFM 4/21/05 12:59 PM Page iv CHAPTER 1 Dedication To my husband Richards, and sons Rich and Tom.

5 1290.ChFM 4/21/05 12:59 PM Page v CHAPTER 1 Preface This text was written specifically for health information management students enrolled in baccalaureate degree programs and for practicing health information management professionals. This text focuses on applying statistical techniques to problems in health care. Because the focus here is on application, it is assumed that the student has had a previous course in probability theory and the normal distribution. This text is set up so that students can either use the Jones and Bartlett Publishers website that supports this book or input the data for each problem using their own statistical software. It is not the intent of this book to teach the student how to use SPSS, Microsoft Excel, or any other type of statistical package or electronic spreadsheet. These programs are included in this text as examples only; I am not endorsing any of these products. My goal in writing this book was to introduce students and professionals to how statistical techniques can be used to describe and make inferences from health care data. There are many statistical books available on the market, but none is directed specifically to the health information management profession. Also, because there are other texts that introduce the student to traditional hospital statistics such as average length of stay and total inpatient service days, they are not covered in this text. v

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7 1290.ChFM 4/21/05 12:59 PM Page vii CHAPTER 1 Contents Chapter 1 Commonly Used Frequency Measures in Health Care 1 Key Terms 1 Learning Objectives 1 Ratios, Proportions, and Rates 4 Population-Based Mortality Measures 6 Frequently Used Measures of Morbidity 18 Relative Measures of Disease Frequency 20 Kaplan-Meier Survival Analysis 26 Conclusion 29 Appendix 1 A 31 Chapter 2 Graphic Display of Data 39 Key Terms 39 Learning Objectives 39 Construction of Tables 40 Charts 44 Conclusion 59 Appendix 2 A 61 Chapter 3 Introduction to Measurement 65 Key Terms 65 Learning Objectives 65 What Is Measurement? 66 Validity 68 Sensitivity, Specificity, and Predictive Value of Measure 70 Reliability 72 Timeliness 75 Scales of Measurement 75 vii

8 1290.ChFM 4/21/05 12:59 PM Page viii viii CONTENTS Conclusion 78 Appendix 3 A 80 Chapter 4 Measures of Central Tendency and Variability 85 Key Terms 85 Learning Objectives 85 Measures of Central Tendency 86 Measures of Variability 95 Calculating Measures of Central Tendency and Variability Using SPSS 99 Dichotomous Data 100 Grouped Frequency Distributions 100 Conclusion 113 Appendix 4 A 115 Chapter 5 The Normal Distribution and Statistical Inference 125 Key Terms 125 Learning Objectives 125 Characteristics of the Normal Distribution 126 The Standard Normal Distribution (z Distribution) 128 Statistical Inference 133 Central Limit Theorem 134 Standard Error of the Mean 136 Confidence Intervals 138 Sampling Methods 139 Hypothesis Testing and Statistical Significance 140 Level of Significance 142 The p Value 143 Using Computer Software to Solve Problems 149 Conclusion 150 Appendix 5 A 152 Chapter 6 Hypothesis Testing of the Difference Between Two Population Means 159 Key Terms 159 Learning Objectives 159 The Standard Normal Distribution and the z Test for Comparing Population Means 160 The z Test for Comparing Two Population Proportions 164 The t Test 166 Conclusion 180 Appendix 6 A 181

9 1290.ChFM 4/21/05 12:59 PM Page ix CONTENTS ix Chapter 7 Analysis of Variance 187 Key Terms 187 Learning Objectives 187 Analysis of Variance 188 Anova in the Three-Sample Case 194 Statistical Power 200 Conclusion 202 Appendix 7 A 203 Chapter 8 Correlation and Linear Regression 209 Key Terms 209 Learning Objectives 209 Characteristics of Pearson r 210 Calculation of the Pearson r 213 Introduction to Linear Regression 218 Interpretation of the Standard Error of the Estimate 226 Hypothesis Testing 228 Coefficient of Determination 229 F Test 229 Regression Model for Length of Stay and Total Charges 231 Conclusion 245 Appendix 8 A 246 Chapter 9 Chi-Square 251 Key Terms 251 Learning Objectives 251 Chi-Square (X 2 ) Tests 253 The X 2 Test of Independence 254 Examination of Residuals 258 Yates Correction for Continuity 258 Phi Coefficient 258 Contingency Coefficient 260 Cramer s V 260 Fisher s Exact Test 261 X 2 Goodness of Fit 264 X 2 Test for Paired Data McNemar Test 266 Conclusion 268 Appendix 9 A 270 Chapter 10 Nonparametric Methods 275 Key Terms 275 Learning Objectives 275 The Spearman RHO Rank Order Correlation Coefficient 275

10 1290.ChFM 4/21/05 12:59 PM Page x x CONTENTS Location Tests for Single and Paired Samples 279 Mann-Whitney Wilcoxon Test 287 Kruskal-Wallis Test 291 Conclusion 295 Appendix 10 A 296 Appendix A: Glossary 301 Appendix B: Statistical Tables 313 Appendix C: Frequency Distribution of Discharges by DRG, Critical Care Hospital, 2004: An Index to the Number of Cases by DRG 327 Appendix D: Answers and Solutions 331 Index 383