Biostatistics - The Carter Center

275 Pages·2007·0.84 MB·English

LECTURE NOTES

For Health Science Students

Biostatistics

Getu Degu
Fasil Tessema

University of Gondar

In collaboration with the Ethiopia Public Health Training Initiative, The Carter Center,
the Ethiopia Ministry of Health, and the Ethiopia Ministry of Education

January 2005
Funded under USAID Cooperative Agreement No. 663-A-00-00-0358-00.

Produced in collaboration with the Ethiopia Public Health Training Initiative, The Carter
Center, the Ethiopia Ministry of Health, and the Ethiopia Ministry of Education.

Important Guidelines for Printing and Photocopying
Limited permission is granted free of charge to print or photocopy all pages of this
publication for educational, not-for-profit use by health care workers, students or
faculty. All copies must retain all author credits and copyright notices included in the
original document. Under no circumstances is it permissible to sell or distribute on a
commercial basis, or to claim authorship of, copies of material reproduced from this
publication.

©2005 by Getu Degu and Fasil Tessema

All rights reserved. Except as expressly provided above, no part of this publication may
be reproduced or transmitted in any form or by any means, electronic or mechanical,
including photocopying, recording, or by any information storage and retrieval system,
without written permission of the author or authors.

This material is intended for educational use only by practicing health care workers or
students and faculty in a health care field.
Biostatistics

PREFACE

This lecture note is primarily for Health officer and Medical students
who need to understand the principles of data collection,
presentation, analysis and interpretation. It is also valuable to diploma
students of environmental health, nursing and laboratory technology
although some of the topics covered are beyond their requirements.
The material could also be of paramount importance for an individual
who is interested in medical or public health research.

It has been a usual practice for a health science student in Ethiopia to
spend much of his/her time in search of reference materials on
Biostatistics. Unfortunately, there are no textbooks which could
appropriately fulfill the requirements of the Biostatistics course at the
undergraduate level for Health officer and Medical students. We firmly
believe that this lecture note will fill that gap.
The first three chapters cover basic concepts of Statistics focusing on
the collection, presentation and summarization of data. Chapter four
deals with the basic demographic methods and health service
statistics giving greater emphasis to indices relating to the hospital. In
chapters five and six elementary probability and sampling methods
are presented with practical examples. A relatively comprehensive
description of statistical inference on means and proportions is given
in chapters seven and eight. The last chapter of this lecture note is
about linear correlation and regression.
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General learning objectives followed by introductory sections which
are specific to each chapter are placed at the beginning of each
chapter. The lecture note also includes many problems for the
student, most of them based on real data, the majority with detailed
solutions. A few reference materials are also given at the end of the
lecture note for further reading.

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Acknowledgments

We would like to thank the Gondar College of Medical Sciences and
the Department of Epidemiology and Biostatistics (Jimma University)
for allowing us to use the institutions resources while writing this
lecture note. We are highly indebted to the Carter Center with out
whose uninterrupted follow up and support this material would have
not been written. we wish to thank our students whom we have
instructed over the past years for their indirect contribution to the
writing of this lecture note.

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Table of Contents

Preface i
Acknowledgements iii
Table of contents iv

Chapter One : Introduction to Statistics
1.1 Learning Objectives 1
1.2 Introduction 1
1.3 Rationale of studying Statistics 5
1.4 Scales of measurement 7

Chapter Two: Methods of Data collection,
Organization and presentation

2.1 Learning Objectives 12
2.2 Introduction 12
2.3 Data collection methods 13
2.4 Choosing a method of data collection 19
2.5 Types of questions 22
2.6 Steps in designing a questionnaire 27
2.7 Methods of data organization and presentation 32

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Chapter Three : Summarizing data

3.1 Learning Objectives 61
3.2 Introduction 61
3.3 Measures of Central Tendency 63
3.4 Measures of Variation 74

Chapter Four : Demographic Methods and
Health Services Statistics

4.1 Learning Objectives 95
4.2 Introduction 95
4.3 Sources of demographic data 97
4.4 Stages in demographic transition 103
4.5 Vital Statistics 107
4.6 Measures of Fertility 109
4.7 Measures of Mortality 114
4.8 Population growth and Projection 117
4.9 Health services statistics 119

Chapter Five : Elementary Probability
and probability distribution

5.1 Learning Objectives 126
5.2 Introduction 126
5.3 Mutually exclusive events and the additive law 129
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5.4 Conditional Probability and the multiplicative law 131
5.5 Random variables and probability distributions 135

Chapter Six : Sampling methods

6.1 Learning Objectives 150
6.2 Introduction 150
6.3 Common terms used in sampling 151
6.4 Sampling methods 153
6.5 Errors in Sampling 160

Chapter seven : Estimation

7.1 Learning Objectives 163
7.2 Introduction 163
7.3 Point estimation. 164
7.4 Sampling distribution of means 165
7.5 Interval estimation (large samples) 169
7.6 Sample size estimation 179
7.7 Exercises 185

Chapter Eight : Hypothesis Testing

8.1 Learning Objectives 186
8.2 Introduction 186
8.3 The Null and Alternative Hypotheses 188
8.4 Level of significance 191
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8.5 Tests of significance on means and
proportions (large samples) 193
8.6 One tailed tests 204
8.7 Comparing the means of small samples 208
8.8 Confidence interval or P-value? 219
8.9 Test of significance using the Chi-square
and Fisher’s exact tests 221
8.10 Exercises 229

Chapter Nine: Correlation and Regression

9.1 Learning Objectives 231
9.2 Introduction 231
9.3 Correlation analysis 232
9.4 Regression analysis 241

Appendix : Statistical tables 255

References 263

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List of Tables

Table 1 overall immunization status of children in
adamai Tullu Woreda, Feb 1995 46
Table 2: TT immunization by marital status of the
woment of childbearing age, assendabo
town jimma Zone, 1996 47
Table 3 Distribution of Health professional by sex
and residence 48
Table 4 Area in one tall of the standard normal curve 255
Table 5 Percentage points of the t Distribution 258
Table 6 Percentage points of the Chi-square distribution 260
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