Principles of Epidemiology in Public Health Practice, Third EditionAn Introduction to Applied Epidemiology and Biostatistics

This is an online version of a printed textbook. It is not intended to be an online course.

Refer to the book or to the electronic PDF version (511 pages) for printable versions of text, figures, and tables.

Book originally published: October 2006
Book updated: November 2011


This course [book] was developed by the Centers for Disease Control and Prevention (CDC) as a self-study course. Continuing education is available for certified public health educators, nurses, physicians, pharmacists, veterinarians, and public health professionals. CE is available only through the CDC/ATSDR Training and Continuing Education Online system at

To receive CE, you must register for the course (SS1978) and complete the evaluation and examination online. You must achieve a score of 70% or higher to pass the examination. If you do not pass the first time, you can take the exam a second time.

For more information about continuing education, call 1-800-41-TRAIN (1-800-418-7246) or by e-mail at


Students who successfully complete this course should be able to correctly:

  • Describe key features and applications of descriptive and analytic epidemiology.
  • Calculate and interpret ratios, proportions, incidence rates, mortality rates, prevalence, and years of potential life lost.
  • Calculate and interpret mean, median, mode, ranges, variance, standard deviation, and confidence interval.
  • Prepare and apply tables, graphs, and charts such as arithmetic-scale line, scatter diagram, pie chart, and box plot.
  • Describe the processes, uses, and evaluation of public health surveillance.
  • Describe the steps of an outbreak investigation.

Course Design

This course covers basic epidemiology principles, concepts, and procedures useful in the surveillance and investigation of health-related states or events. It is designed for federal, state, and local government health professionals and private sector health professionals who are responsible for disease surveillance or investigation. A basic understanding of the practices of public health and biostatistics is recommended.

Course Materials

The course materials consist of six lessons. Each lesson presents instructional text interspersed with relevant exercises that apply and test knowledge and skills gained.

Lesson One: Introduction to Epidemiology

Key features and applications of descriptive and analytic epidemiology

Lesson Two: Summarizing Data

Calculation and interpretation of mean, median, mode, ranges, variance, standard deviation, and confidence interval

Lesson Three: Measures of Risk

Calculation and interpretation of ratios, proportions, incidence rates, mortality rates, prevalence, and years of potential life lost

Lesson Four: Displaying Public Health Data

Preparation and application of tables, graphs, and charts such as arithmetic-scale line, histograms, pie chart, and box plot

Lesson Five: Public Health Surveillance

Processes, uses, and evaluation of public health surveillance in the United States

Lesson Six: Investigating an Outbreak

Steps of an outbreak investigation


A Glossary that defines the major terms used in the course is also provided at the end of Lesson Six.

Supplementary Materials

In addition to the course materials, students may want to use the following:

  • A calculator with square root and logarithmic functions for some of the exercises.
  • A copy of Heymann, DL, ed. Control of Communicable Diseases Manual, 18th edition, 2004, for reference. Available from the American Public Health Association (202) 777-2742.

General Instructions

Self-study courses are “self-paced.” We recommend that a lesson be completed within two weeks. To get the most out of this course, establish a regular time and method of study. Research has shown that these factors greatly influence learning ability.

Each lesson in the course consists of reading, exercises, and a self-assessment quiz.

Reading Assignments

Complete the assigned reading before attempting to answer the self-assessment questions. Read thoroughly and re-read for understanding as necessary. A casual reading may result in missing useful information which supports main themes. Assignments are designed to cover one or two major subject areas. However, as you progress, it is often necessary to combine previous learning to accomplish new skills. A review of previous lessons may be necessary. Frequent visits to the Glossary may also be useful.


Exercises are included within each lesson to help you apply the lesson content. Some exercises may be more applicable to your workplace and background than others. You should review the answers to all exercises since the answers are very detailed. Answers to the exercises can be found at the end of each lesson. Your answers to these exercises are valuable study guides for the final examination.

Self-Assessment Quizzes

After completing the reading assignment, answer the self-assessment quizzes before continuing to the next lesson. Answers to the quizzes can be found at the end of the lesson. After passing all six lesson quizzes, you should be prepared for the final examination.

  • Self-assessment quizzes are open book.
  • Unless otherwise noted, choose ALL CORRECT answers.
  • Do not guess at the answer.
  • You should score at least 70% correct before continuing to the next lesson.

Tips for Answering Questions

  • Carefully read the question.
    Note that it may ask, “Which is CORRECT?” as well as “Which is NOT CORRECT?” or “Which is the EXCEPTION?”
  • Read all the choices given.
    One choice may be a correct statement, but another choice may be more nearly correct or complete for the question that is asked.

Final Examination and Course Evaluation

The final examination and course evaluation are available only on-line. The final requirement for the course is an open-book examination. We recommend that you thoroughly review the questions included with each lesson before completing the exam.

It is our sincere hope that you will find this undertaking to be a profitable and satisfying experience. We solicit your constructive criticism at all times and ask that you let us know whenever you have problems or need assistance.

Continuing Education

To receive continuing education for completing the self-study course, go to the CDC/ATSDR Training and Continuing Education Online at and register as a participant. You will need to register for the course (SS1978) and complete the course evaluation and exam online. You will have to answer at least 70% of the exam questions correctly to obtain continuing education credits/contact hours and a certificate. For more information about continuing education, please call 1-800-41 TRAIN (1-800-418-7246) or go to

Continuing Education Accreditation Statements

Origination Date: November 4, 2011
Renewal Date: November 4, 2013
Expiration Date: November 4, 2015

CDC, our planners, and our content experts wish to disclose they have no financial interests or other relationships with the manufacturers of commercial products, suppliers of commercial services, or commercial supporters. Planners have reviewed content to ensure there is no bias.

Content will not include any discussion of the unlabeled use of a product or a product under investigational use.

CDC does not accept commercial support.

Continuing Medical Education for Physicians (CME):

The Centers for Disease Control and Prevention is accredited by the Accreditation Council for Continuing Medical Education (ACCME®) to provide continuing medical education for physicians.

The Centers for Disease Control and Prevention designates this enduring activity for a maximum of 17 AMA PRA Category 1 Credits™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Continuing Medical Education for Nurses (CNE):

The Centers for Disease Control and Prevention is accredited as a provider of Continuing Nursing Education by the American Nurses Credentialing Center’s Commission on Accreditation.

This activity provides 17 contact hours.

Continuing Education for Certified Health Educators (CECH):

Sponsored by the Centers for Disease Control and Prevention, a designated provider of continuing education contact hours (CECH) in health education by the National Commission for Health Education Credentialing, Inc. This program is designed for Certified Health Education Specialists (CHES) to receive up to 17 Category I CECH in health education. CDC provider number GA0082.

Continuing Education for Pharmacists (CPE):

ACPE logo

The Centers for Disease Control and Prevention is accredited by the Accreditation Council for Pharmacy Education as a provider of continuing pharmacy education.

This program is a designated event for pharmacists to receive 1.7Contact Hours in pharmacy education. The Universal Activity Number is 0387-0000-13-143-H04-P.

Course Category: This activity has been designated as Application-Based.

Cost: There is no fee related to the web-based version of the activity. There is a fee charged for the version ordered from the Public Health Foundation.

IACET Continuing Education Units (CEU):

The CDC has been approved as an Authorized Provider by the International Association for Continuing Education and Training (IACET), 1760 Old Meadow Road, Suite 500, McLean, VA 22102. The CDC is authorized by IACET to offer 1.7 ANSI/IACET CEU’s for this program.

Continuing Education for Veterinarians (AAVSB/RACE):

This program was reviewed and approved by the AAVSB RACE program for 20 hours of continuing education in jurisdictions which recognize AAVSB RACE approval. Please contact the AAVSB RACE program if you have any comments/concerns regarding this program’s validity or relevancy to the veterinary profession.

Course Evaluation

Even if you are not interested in continuing education, we still encourage you to complete the course evaluation. To do this, go to and register as a participant. You will then need to register for the course (SS1978) and complete the course evaluation online. There is no cost to obtain continuing education online. Your comments are valuable to us and will help to revise the self-study course in the future.

Ordering Information

A hard-copy of the text can be obtained from the Public Health Foundation. Specify Item No. SS1978 or SS1000 when ordering.


Developed by

  • U.S. Department of Health and Human Services
  • Centers for Disease Control and Prevention (CDC)
  • Office of Workforce and Career Development (OWCD)
  • Career Development Division (CDD)
  • Atlanta, Georgia 30333

Technical Content

  • Richard C. Dicker, MD, MSc, Lead Author, CDC/OWCD/CDD (retired)
  • Fátima Coronado, MD, MPH, CDC/OWCD/CDD
  • Denise Koo, MD, MPH, CDC/OWCD/CDD
  • Roy Gibson Parrish, II, MD

Development Team

  • Sonya D. Arundar, MS, CDC (contractor)
  • Ron Teske, MS, CDC (contractor)
  • Susan Baker Toal, MPH, Public Health Consultant
  • Nancy M. Hunt, MPH, CDC (ORISE Fellow)
  • Susan D. Welch, MEd, Georgia Poison Center
  • Cassie Edwards, CDC (contractor)

Planning Committee

  • Christopher K. Allen, RPh, MPH, CDC
  • W. Randolph Daley, DVM, MPH, CDC
  • Patricia Drehobl, RN, MPH
  • Sharon Hall, RN, PhD, CDC
  • Dennis Jarvis, MPH, CHES, CDC
  • Denise Koo, MD, MPH, CDC


  • Sonya D. Arundar, MS, CDC (contractor)
  • Lee Oakley, CDC (retired)
  • Jim Walters, CDC

Technical Reviewers

  • Tomas Aragon, MD, DrPH, San Francisco Department of Public Health
  • Diane Bennett, MD, MPH, CDC
  • Danae Bixler, MD, MPH, West Virginia Bureau for Public Health
  • R. Elliot Churchill, MS, MA, CDC (retired)
  • Roxanne Ereth, MPH, Arizona Department of Health Services
  • Stephen Everett, MPH, Yavapai County Community Health Services, Arizona
  • Michael Fraser, PhD, National Association of County and City Health Officials
  • Nancy C. Gathany, MEd, CDC
  • Marjorie A.Getz, MPHIL, Bradley University, Illinois
  • John Mosely Hayes, DrPH, MBA, MSPH, Tribal Epidemiology Center United South and Eastern Tribes, Inc., Tennessee
  • Richard Hopkins, MD, MSPH, Florida Department of Health
  • John M. Horan, MD, MPH, Georgia Division of Public Health
  • Christina M. Bruton Kwon, MSPH, Science Applications International Corporation, Atlanta
  • Edmond F. Maes, PhD, CDC
  • Sharon McDonnell, MD, MPH, Darmouth Medical School
  • William S. Paul, MD, MPH, Chicago Department of Public Health
  • James Ransom, MPH, National Association of County and City Health Officials
  • Lynn Steele, MS, CDC
  • Donna Stroup, PhD, MSc, American Cancer Society
  • Douglas A. Thoroughman, PhD, MS CDC
  • Kirsten T. Weiser, MD, Darmouth Hitchcock Medical School
  • Celia Woodfill, PhD, California Department of Health Services

Field Test Participants

  • Sean Altekruse, DVM, MPH, PhD, U.S. Public Health Service
  • Gwen A. Barnett, MPH, CHES, CDC
  • Jason Bell, MD, MPH
  • Lisa Benaise, MD, Med Immune, Inc., Maryland
  • Amy Binggeli, DrPH, RD, CHES, CLE, Imperial County Public Health Department, California
  • Kim M. Blindauer, DVM, MPH, Agency for Toxic Substances and Disease Registry
  • R. Bong, RN, BSN, Federal Bureau of Prisons
  • Johnna L. Burton, BS, CHES, Tennessee Department of Health
  • Catherine C. Chow, MD, MPH, Hawaii Department of Health
  • Janet Cliatt, MT, CLS(NCA), National Institutes of Health
  • Catherine Dentinger, FNP, MS, New York City Department of Health and Mental Hygiene
  • Veronica Gordon, BSN, MS, Indian Health Service, New Mexico
  • Susan E. Gorman, PharmD, DABAT, CDC
  • Deborah Gould, PhD, CDC
  • Juliana Grant, MD, MPH, CDC
  • Lori Evans Hall, PharmD, CDC
  • Nazmul Hassan, MS, Food and Drug Administration
  • Daniel L. Holcomb, BS, Agency for Toxic Substances and Disease Registry
  • Asim A. Jani, MD, MPH FACP, CDC
  • Charletta L. Lewis, BSN, Wellpinit Indian Health Service, Washington
  • Sheila F. Mahoney, CNM, MPH, National Institutes of Health
  • Cassandra Martin, MPH, CHES, Georgia Department of Human Resources
  • Joan Marie McFarland, AS, BSN, MS, Winslow Indian Health Care Center, Arizona
  • Rosemarie McIntyre, RN, MS, CHES, CDC
  • Gayle L. Miller, DVM, Jefferson County Department of Health and Environment, Colorado
  • Long S. Nguyen, MPH, CHES, NIH
  • Paras M. Patel, RPh, Food and Drug Administration
  • Rossanne M. Philen, MD, MS, CDC
  • Alyson Richmond, MPH, CHES, CDC (contractor)
  • Glenna A. Schindler, MPH, RN, CHES, Healthcare Services Group, Missouri
  • Sandra K. Schumacher, MD, MPH, CDC
  • Julie R. Sinclair, MA, DVM, MPH, CDC
  • Nita Sood, RPh, PharmD, U.S. Public Health Service
  • P. Lynne Stockton, VMD, MS, ELS(D), CDC
  • Jill B. Surrency, MPH, CHES, CDC (contractor)
  • Joyce K. Witt, RN, CDC

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services.