Public Health Information Network (PHIN) Series II - PowerPoint PPT Presentation

Public health information network phin series ii l.jpg
Download
1 / 107

Public Health Information Network (PHIN) Series II Outbreak Investigation Methods: From Mystery to Mastery Series II Session III “Study Design” Series II Sessions Access Series Files Online http://www.vdh.virginia.gov/EPR/Training.asp Session slides Session activities (when applicable)

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

Public Health Information Network (PHIN) Series II

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Public health information network phin series ii l.jpg

Public Health Information Network (PHIN) Series II

Outbreak Investigation Methods:

From Mystery to Mastery


Series ii session iii l.jpg

Series IISession III

“Study Design”


Series ii sessions l.jpg

Series II Sessions


Access series files online http www vdh virginia gov epr training asp l.jpg

Access Series Files Onlinehttp://www.vdh.virginia.gov/EPR/Training.asp

  • Session slides

  • Session activities (when applicable)

  • Session evaluation forms

  • Speaker biographies

    Alternate Web site:http://www.sph.unc.edu/nccphp/phtin/index.htm


Site sign in sheet l.jpg

Site Sign-in Sheet

Please submit your site sign-in sheet and

session evaluation forms to:

Suzi Silverstein

Director, Education and Training

Emergency Preparedness & Response Programs

FAX: (804) 225 - 3888


Session overview l.jpg

Session Overview

  • Session I summary and review: How we arrived at the research hypothesis

  • Analytic Epidemiology

  • Developing and testing hypotheses

  • Study Designs:

    • selection, implementation, and data analysis


Today s presenters l.jpg

Today’s Presenters

Amy Nelson, PhD, MPH

Epidemiologist

NC Center for Public Health Preparedness

Sarah Pfau, MPH

Moderator


Study design learning objectives l.jpg

“Study Design” Learning Objectives

  • Understand what an analytic study contributes to an epidemiological outbreak investigation

  • Understand the differences in methodology between cohort, case-control, clinical trial, and cross-sectional study designs

  • Be able to describe the advantages and disadvantages of alternative study designs


Study design learning objectives cont d l.jpg

“Study Design” Learning Objectives (cont’d.)

  • Know how to assess which study design to apply during an outbreak investigation

  • Understand how to select cases and controls in a case-control study design

  • Know how to interpret odds ratios from case-control study data and risk ratios from cohort study data


Session i review l.jpg

Session I Review


Session i review12 l.jpg

Session I Review

  • Detected an outbreak of gastroenteritis at a university in Texas, based on a March 11 complaint from a student

  • Conducted:

    • active case finding

    • chart reviews

    • hypothesis generating interviews

  • 75 cases detected by March 12


Session i review cont d l.jpg

Session I Review (cont’d.)

  • Collected stool specimens

    • All negative for bacterial pathogens

    • Assume viral pathogen

  • Earliest date of exposure was March 5

  • Conducted interviews with 7 of the earliest cases (all students)

    • Only commonality was 6 of 7 reported eating at deli bar of main campus cafeteria


Session i review cont d14 l.jpg

Session I Review (cont’d.)

  • Developed a leading hypothesis with the main campus cafeteria as the suspect

    • No source food identified

  • Interviewed 30 of 31 cafeteria staff members

    • Staff member who declined interview worked at deli bar*

      * Today’s session includes a follow up investigation with this staff member


Session i review cont d15 l.jpg

Session I Review (cont’d.)

  • Investigators closed deli bar on March 12th based on:

    • Link between 6 out of 7 interviewed cases and a common food source

    • Several unsanitary food handling practices identified via an environmental health investigation


Basic steps of an outbreak investigation l.jpg

Basic Steps of An Outbreak Investigation

  • Verify the diagnosis and confirm the outbreak

  • Define a case and conduct case finding

  • Tabulate and orient data: time, place, person

  • Take immediate control measures

  • Formulate and test hypothesis

  • Plan and execute additional studies

  • Implement and evaluate control measures

  • Communicate findings


Analytic epidemiology l.jpg

Analytic Epidemiology

Hypotheses


Descriptive vs analytic epidemiology l.jpg

Descriptive vs. Analytic Epidemiology

  • Descriptive Epidemiology deals with the questions: Who, What, When, and Where

  • Analytic Epidemiology deals with the remaining questions: Why and How


Analytic epidemiology19 l.jpg

Analytic Epidemiology

  • Used to help identify the cause of disease

  • Typically involves designing a study to test hypotheses developed using descriptive epidemiology


Exposure and outcome l.jpg

Exposure and Outcome

A study considers two main factors:

exposure and outcome

  • Exposure refers to factors that might influence one’s risk of disease

  • Outcome refers to case definitions


Case definition l.jpg

Case Definition

  • A set of standard diagnostic criteria that must be fulfilled in order to identify a person as a case of a particular disease

  • Ensures that all persons who are counted as cases actually have the same disease

  • Typically includes clinical criteria (lab results, symptoms, signs) and sometimes restrictions on time, place, and person


Developing hypotheses l.jpg

Developing Hypotheses

  • A hypothesis is an educated guess about an association that is testable in a scientific investigation

  • Descriptive data provide information to develop hypotheses

  • Hypotheses tend to be broad initially and are then refined to have a narrower focus


Example l.jpg

Example

  • Hypothesis: People who ate at the church picnic were more likely to become ill

    • Exposure is eating at the church picnic

    • Outcome is illness – this would need to be defined, for example, ill persons are those who have diarrhea and fever

  • Hypothesis: People who ate the egg salad at the church picnic were more likely to have laboratory-confirmed Salmonella

    • Exposure is eating egg salad at the church picnic

    • Outcome is laboratory confirmation of Salmonella


Tx case study l.jpg

TX Case Study

Hypothesis and Study Design


What do we know l.jpg

What do we know?

  • We know…

    • 75 cases reported by March 12 – all were students who lived on campus

    • All of cases sampled (n=7) reported eating at the main campus cafeteria

      • 6 of 7 at the deli bar

    • No illness among off-campus students, faculty, or community members


What do we suspect l.jpg

What do we suspect?

  • We suspect the main cafeteria is the source of infection

  • We also suspect the deli bar, in particular, may be the outbreak source


What can we prove l.jpg

What can we “prove”?

  • Can we “prove” it?

    • Need to conduct an analytic study

    • Need a testable hypothesis


What hypothesis will be tested l.jpg

What hypothesis will be tested?

  • Main cafeteria vs. other dining halls?

  • Within the main cafeteria:

    • Deli bar vs. grill?

    • Salad bar vs. hot entrée?

  • Food item vs. food handler at deli bar?


Our hypothesis l.jpg

Our Hypothesis

A viral infection was spread by food(s) or beverage(s) served at the university’s main cafeteria between March 5 and 10.


Source population l.jpg

Source Population

Town residents (39,000)

Students (12,000)

2400 on campus

2000 meal plan


Which study design l.jpg

Which Study Design?


Types of analytic studies l.jpg

Types of Analytic Studies

Two main categories:

  • Experimental

  • Observational

  • Experimental – exposure status is assigned

  • Observational – exposure status is not assigned


  • Experimental studies l.jpg

    Experimental Studies

    • Can involve individuals or communities

    • Assignment of exposure status can be random or non-random

    • The non-exposed group can be untreated (placebo) or given a standard treatment

    • Most common is a randomized clinical trial


    Experimental study examples l.jpg

    Experimental Study Examples

    • Randomized clinical trial to determine if giving magnesium sulfate to pregnant women in preterm labor decreases the risk of their babies developing cerebral palsy

    • Randomized community trial to determine if fluoridation of the public water supply decreases dental cavities


    Observational studies l.jpg

    Observational Studies

    Three main types:

    • Cross-sectional study

    • Cohort study

    • Case-control study


    Cross sectional studies l.jpg

    Cross-Sectional Studies

    • Exposure and outcome status are determined at the same time

    • Examples include:

      • Behavioral Risk Factor Surveillance System (BRFSS) - http://www.cdc.gov/brfss/

      • National Health and Nutrition Surveys (NHANES) - http://www.cdc.gov/nchs/nhanes.htm

    • Also include most opinion and political polls


    Cohort study l.jpg

    Cohort Study


    Definition of a cohort l.jpg

    Definition of a Cohort

    In Epidemiology, “Any designated group of individuals who are followed or traced over a period of time.”

    Last, JM. A Dictionary of Epidemiology, 3rd ed. New York: Oxford University Press, 1995


    Cohort studies l.jpg

    Cohort Studies

    Study

    Population

    Exposure is

    self selected

    Non-exposed

    Exposed

    Follow through

    time

    Disease

    No Disease

    Disease

    No Disease


    Cohort studies prospective vs retrospective l.jpg

    Cohort Studies:Prospective vs. Retrospective


    Cohort forward directionality l.jpg

    Cohort: Forward Directionality

    ExposureOutcome

    Cohort Timeline

    Ill?

    Not Ill?

    Exposed

    Research Timeline


    Cohort study42 l.jpg

    Cohort Study

    Steps in a Cohort Study:

    • Identify Cohort

    • Administer Questionnaire

    • Analyze Data


    Cohort study43 l.jpg

    Cohort Study

    Step 1 – Identify cohort

    • Entire student body (n=12,000)

    • On-campus students (n=2400)

    • On campus students with meal plan who mainly ate at cafeteria (n=2000)

    • Sick students (n=75)

  • Do not select cohort so that either everyone is exposed or everyone is diseased


  • Cohort study44 l.jpg

    Cohort Study

    Step 2 – Administer questionnaire

    • Step 2a – Determine exposure status

      • Main cafeteria

      • Deli bar

      • Food item

    • Step 2b – Determine disease status

      • Importance of well-defined case definition


    Cohort study example l.jpg

    Cohort Study Example

    Dartmouth University: 698 (13.8%) of 5060 students had conjunctivitis in spring 2002

    • To identify risk factors...

      • web-based questionnaire set up

      • E-mail sent to 3682 undergraduates

      • No data entry-rapid analysis

    • 1832 (50%) responded

      An outbreak of conjunctivitis due to atypical Streptococcus

      pneumoniae. N Engl J Med. 2003;348 (12):1112-21.


    Cohort study46 l.jpg

    Cohort Study

    Step 3 – Analyze data


    Interpreting a risk ratio l.jpg

    Interpreting a Risk Ratio

    The risk ratio is the ratio of the risk of disease in exposed individuals to the risk of disease in unexposed individuals

    • RR=1.0 = no association between exposure and disease

    • RR>1.0 = positive association

    • RR<1.0 = negative association


    Interpreting a risk ratio48 l.jpg

    Interpreting a Risk Ratio

    Example: Outbreak of conjunctivitis at Dartmouth College

    • RR = 2.5

    • Disease = Conjunctivitis

    • Exposure = Attended a fraternity / sorority party

      “Students who attended a fraternity or sorority party had 2.5 times the risk of having conjunctivitis compared to students who did not attend a fraternity or sorority party”


    Cohort study example49 l.jpg

    Cohort Study Example

    • Recent norovirus outbreaks on cruise ships

    • Attempt to interview all passengers

    • Collect food history information

    MMWR: December 13, 2002 / 51(49);1112-1115


    Cohort study examples l.jpg

    Cohort Study Examples

    • Shigellosis among swimmers in a Georgia park

      • Used park registry to identify park visitors

    • Whirlpools and Methicillin-Resistant Staphylococcus aureus

      • Occurred on a college football team


    Question answer opportunity l.jpg

    Question & Answer Opportunity


    5 minute break l.jpg

    5 Minute Break


    Case control study l.jpg

    Case-Control Study


    Case control studies l.jpg

    Case-control Studies

    Had Exposure

    No Exposure

    Had Exposure

    No Exposure

    Cases

    Controls

    Study

    Population


    Case control backwards directionality l.jpg

    Case-Control:Backwards Directionality

    ExposureOutcome

    Cohort Timeline

    Exposed?

    Not exposed?

    Ill

    Research Timeline


    Case control study56 l.jpg

    Case-Control Study

    Steps in a Case-Control Study:

    • Identify the source population

    • Establish a case definition and select cases

    • Select controls

    • Analyze data


    Case control study57 l.jpg

    Case-Control Study

    Step 1 - Identify source population

    • Represents the population that gives rise to the cases; is similar to a cohort study

    • In the Texas case study, the source population is: all students who live on-campus


    Case control study58 l.jpg

    Case-Control Study

    Step 2 – Establish a case definition and select cases

    • A standard set of criteria for deciding disease status

      • Clinical criteria, time, place, and person


    Case study case definition l.jpg

    Study Hypothesis

    A viral infection spread by food(s) or beverage(s) served at the university’s main cafeteria between March 5 and 10

    Case definition

    Vomiting or diarrhea (≥3 loose bowel movements during a 24-hour period)

    Onset on or after March 5, 1998

    On-campus student seen at an emergency room or the Student Health Center

    Case Study Case Definition


    Case control study60 l.jpg

    Case-Control Study

    Step 3 – Select Controls

    • Represent source population

      • On-campus students in Texas case study

    • Collect same exposure information as for cases


    Case control study61 l.jpg

    Case-Control Study

    Step 3 – Select Controls (cont’d.)

    • Sources of controls

      • Random sample

      • Friends


    Case control study62 l.jpg

    Case-Control Study

    Step 4 – Analyze Data


    Interpreting an or l.jpg

    Interpreting an OR

    The odds ratio is interpreted in the same way as a risk ratio:

    • OR=1.0 = no association between exposure and disease

    • OR>1.0 = positive association

    • OR<1.0 = negative association


    Interpreting an or64 l.jpg

    Interpreting an OR

    Example: Hepatitis A outbreak investigation

    • OR = 12.0

    • Disease = Hepatitis A

    • Exposure = Eating at restaurant X in April 2003

      “Among those with Hepatitis A, the odds of having eaten at restaurant X in April, 2003 is 12 times greater among the cases than among the controls.”


    Case control study examples l.jpg

    Case-Control Study Examples

    • Study to determine an association between autism and vaccination

    • Study to determine an association between lung cancer and radon exposure

    • Study to determine an association between salmonella infection and eating at a fast food restaurant


    Activity 1 l.jpg

    Activity 1

    Please see: http://www.vdh.virginia.gov/EPR/Training.asp

    for links to Session III activity questions and answers that you can print out.

    Answers are also provided on the next slide.


    5 minute break67 l.jpg

    5 Minute Break


    Cohort versus case control study l.jpg

    Cohort versus Case-Control Study


    Measures of association l.jpg

    Measures of Association


    Activity 2 l.jpg

    Activity 2

    Please see: http://www.vdh.virginia.gov/EPR/Training.asp

    for links to Session III activity questions and answers that you can print out.

    Answers are also provided on the next slide.


    Activity 3 choose a study design to investigate the source of the texas outbreak l.jpg

    Activity 3 Choose a study design to investigate the source of the Texas outbreak

    Completion time: 5 minutes


    Matching in case control studies l.jpg

    Matching in Case-Control Studies


    Matching in case control studies74 l.jpg

    Matching in Case-Control Studies

    • Makes one or more case and control attributes similar (e.g., age, gender, residence)

    • An unmatched study design is usually preferred


    Matching points to consider l.jpg

    Matching: Points to Consider

    • More complex data analysis required

    • Inability to assess role of matching factor on disease status

      • Do not match on exposure factor

    • Potential for over-matching


    Texas dept of health study design l.jpg

    Texas Dept. of HealthStudy Design

    • Matched case-control study conducted among students at the university


    Hypothesis testing results l.jpg

    Hypothesis Testing Results

    Texas case study:

    • Eating at the main cafeteria was not associated with illness

    • Eating lunch at the deli bar on March 9 or March 10 appeared to be associated with illness

      • Individual food items could not be evaluated

      • Conduct a larger, unmatched case-control study to identify high risk items or practices at deli bar


    Hypothesis testing validity of results l.jpg

    Hypothesis Testing:Validity of Results

    • Selection / participation bias

      • Only 29 of 75 cases interviewed

    • Not enough information on deli bar

    • Matching on a risk factor

      • Can’t evaluate person-to-person transmission


    Refine hypothesis update tx case definition l.jpg

    Refine Hypothesis:Update TX Case Definition

    • On-campus student with vomiting or diarrhea (≥3 loose bowel movements during a 24-hour period)

    • Onset of disease on or after March 5, 1998

    • Member of the university meal plan


    Test the refined hypothesis case control study l.jpg

    Test the Refined Hypothesis:Case-Control Study

    • 40 cases were randomly selected from those reported to TDH by a local emergency room or the Student Health Center

    • 160 controls who did not have nausea, vomiting, or diarrhea since March 5 were randomly selected from the university meal plan list


    Questionnaire administration l.jpg

    Questionnaire Administration

    The TX investigators decided to administer the questionnaire by telephone.

    • Need for fast responses; subjects likely to be out of town

    • Desire for accurate information, high response

    • Anonymity not likely to be an issue

    • Take measures to avoid interviewer bias


    Test the refined hypothesis conduct case control study l.jpg

    Test the Refined Hypothesis:Conduct Case-Control Study

    • Texas study questionnaire administered by telephone March 15 - 23

      • Called students at dormitory room or their home telephone number as recorded in university records

      • Follow-up phone calls were made to students, when possible or necessary


    Test the refined hypothesis carry out case control l.jpg

    Test the Refined Hypothesis:Carry out Case-Control

    • 36 cases and 144 controls were enrolled

    • Casesincluded in the study were similar to all cases with respect to gender, age, year in college, and date of onset


    Test the refined hypothesis case control results l.jpg

    Test the Refined Hypothesis:Case-Control Results

    28 (78%) of the 36 cases reported eating at the deli bar during at

    least one of the implicated meals.


    Test the refined hypothesis case control results85 l.jpg

    Test the Refined Hypothesis:Case-Control Results*

    *Only participants reporting eating at deli bar during Mar 9-10 included


    Interpretation of analysis results l.jpg

    Interpretation of Analysis Results

    • What do we know?

    • What do we suspect?

    • What can we “prove”?


    What do we know87 l.jpg

    What do we know?

    • We know that 125 cases of vomiting or diarrhea have been reported – all students

    • We know the cases were more likely to have eaten at the deli bar Mar 9 – Mar 10

    • We know the pathogen is not bacterial


    What do we suspect88 l.jpg

    What do we suspect?

    • We suspect that cases were more likely to have eaten ham, mayonnaise, and American cheese, but results were not statistically significant

    • We suspect the pathogen is viral

    • We suspect the food was contaminated by cafeteria staff


    What can we prove89 l.jpg

    What can we “prove”?

    • We have “proven” the source came from the deli bar

    • We will probably never “prove” which food was the source

    • We may yet “prove” the pathogen is viral

    • We may yet “prove” the food was contaminated by cafeteria staff


    Interpretation of analysis results90 l.jpg

    Interpretation of Analysis Results

    What questions do we still have?

    • Lab results for viral pathogen

    • Missing food handler who worked at deli bar


    Texas case study additional investigations l.jpg

    Texas Case Study:Additional Investigations


    Additional investigations environmental sampling results l.jpg

    Additional Investigations:Environmental Sampling Results

    • Water and ice samples obtained from the cafeteria on March 12 were negative for fecal coliforms

    • Stool cultures and rectal swabs from the 23 food handlers were negative for bacteria


    Additional investigations the missing food handler l.jpg

    Additional Investigations:The Missing Food Handler

    • The staff member who initially refused to be interviewed worked primarily at the deli bar

    • She finally agreed to be interviewed on March 23, and reported slicing ham on March 9 for use at the deli bar during lunch and dinner that day and lunch on March 10

      • Prepared and served sandwiches for March 9 and 10 meals

      • Wore gloves while slicing ham and while serving at the deli bar


    Additional investigations the missing food handler94 l.jpg

    Additional Investigations:The Missing Food Handler

    • Denied any gastrointestinal illness during the outbreak period

    • Reported her infant had been sick with watery diarrhea since March 7

    • Had not thought that hand washing was an important activity because she wore gloves during food preparation and serving


    Additional investigations viral testing l.jpg

    Additional Investigations:Viral Testing

    • Of 18 fresh stool specimens sent to CDC, 9 (50%) had evidence of Norwalk-like virus (NLV) by reverse transcriptase polymerase chain reaction (RT-PCR)

    • Of the four deli foods available from the implicated meals, only the March 9 ham sample was positive for

      the NLV RNA


    Additional investigations viral testing96 l.jpg

    Additional Investigations:Viral Testing

    • NLV was also detected by RT-PCR in a stool sample from the ill infant of the food handler who prepared the deli sandwiches on March 9

    • The sequence of the amplified product was identical to those PCR products from the ill students and the deli ham


    Texas case study conclusions l.jpg

    Texas Case Study Conclusions

    • The evidence implicates the food handler as the source of the outbreak

    • Diarrheal illness in the food handler’s child preceded the outbreak

    • Food handler prepared ingredients and sandwiches served at the deli bar during the time that her child was ill


    Texas case study conclusions98 l.jpg

    Texas Case Study Conclusions

    • NLV was isolated from the child’s stool and was identical to that obtained from ill students and the deli ham

    • The food handler was not necessarily ill or infected

      • May have transferred contamination directly from her ill infant


    What was that again l.jpg

    What was that again?

    • Focus on Field Epidemiology Newsletter, “Selecting a Study Design” at

      http://www.sph.unc.edu/nccphp/focus/vol2/issue4/study_design.pdf

    • Visit http://www.sph.unc.edu/nccphp/focus/index.htm and click “Read FOCUS” for all newsletters


    Session iii summary l.jpg

    Session III Summary


    Session iii summary101 l.jpg

    Session III Summary

    • An analytic study is used to test scientific hypotheses that may help support actions for specific control measures and to help prevent recurrence of a problem.

    • A case definition with specific criteria helps you select your study population, as long as it does not include the hypothesis.

    • Case-control studies, when conducted properly, are generally adequate and usually more efficient than cohort studies.

    • Cohort studies may be preferable when you work with confined (e.g., easily identifiable and accessible) study populations such as on a cruise ship or at a wedding reception.


    Session iii summary102 l.jpg

    Session III Summary

    • Case-control study controls need to be representative of the source population, and not matched on the exposure factor if matching is used.

    • Risk ratios and odds ratios are the measures used to assess an association between an exposure and illness. Cohort study data analyses yield risk ratios; case-control study data analyses yield odds ratios.


    Next session september 1st 1 00 p m 3 00 p m l.jpg

    Next Session September 1st1:00 p.m. – 3:00 p.m.

    Topic: “Designing Questionnaires”


    References and resources l.jpg

    References and Resources

    • Begier EM, Barrett FK, Mshar PA et al. Body Shaving, Whirlpools, and Football: An Out break of Methicillin-Resistant Staphylococcus aureus Cutaneous Infections in a College Football Team-Connecticut, 2003. Presented at the 53rd Annual Epidemic Intelligence Service Conference. Atlanta, GA. April, 2004.

    • Centers for Disease Control and Prevention (1992). Principles of Epidemiology: 2nd Edition. Public Health Practice Program Office: Atlanta, GA.

    • Centers for Disease Control and Prevention "Gastroenteritis at a University in Texas" http://www.phppo.cdc.gov/phtn/casestudies/classroom/gastro.htm

    • Gordis, L. (2000). Epidemiology: 2nd Edition. W.B. Saunders Company: Philadelphia, PA.

    • Gregg, M.B. (2002). Field Epidemiology: 2nd Edition. Oxford University Press: New York.


    References and resources105 l.jpg

    References and Resources

    • Hennekens, C.H. and Buring, J.E. (1987). Epidemiology in Medicine. Little, Brown and Company: Boston/Toronto.

    • Iwamoto M, Hlady G, Jeter M et al. Shigellosis among Swimmers in a Freshwater Lake-Georgia, 2003. Presented at the 53rd Annual Epidemic Intelligence Service Conference. Atlanta, GA. April, 2004.

    • Kleinbaum, D., Sullivan, K., and Barker, N. (2003). ActivEpi Companion Textbook. Springer-Verlag: New York.

    • Last, J.M. (2001). A Dictionary of Epidemiology: 4th Edition. Oxford University Press: New York.

    • McNeill, A. (January 2002). Measuring the Occurrence of Disease: Prevalence and Incidence. Epid 160 lecture series, UNC Chapel Hill School of Public Health, Department of Epidemiology.


    References and resources106 l.jpg

    References and Resources

    • Morton, R.F, Hebel, J.R., McCarter, R.J. (2001). A Study Guide to Epidemiology and Biostatistics: 5th Edition. Aspen Publishers, Inc.: Gaithersburg, MD.

    • North Carolina Center for Public Health Preparedness. March 2005 Public Health Information Network session: “Descriptive and Analytic Epidemiology.”

      http://www.sph.unc.edu/nccphph/phtin/index.htm

    • University of North Carolina at Chapel Hill School of Public Health, Department of Epidemiology, and the Epidemiologic Research & Information Center (June 1999). ERIC Notebook. Issue 2. http://www.sph.unc.edu/courses/eric/eric_notebooks.htm

      .


    References and resources107 l.jpg

    References and Resources

    • University of North Carolina at Chapel Hill School of Public Health, Department of Epidemiology, and the Epidemiologic Research & Information Center (July 1999). ERIC Notebook. Issue 3. http://www.sph.unc.edu/courses/eric/eric_notebooks.htm

    • University of North Carolina at Chapel Hill School of Public Health, Department of Epidemiology, and the Epidemiologic Research & Information Center (September 1999). ERIC Notebook. Issue 5. http://www.sph.unc.edu/courses/eric/eric_notebooks.htm

    • University of North Carolina at Chapel Hill School of Public Health, Department of Epidemiology (August 2000). Laboratory Instructor’s Guide: Analytic Study Designs. Epid 168 lecture series. http://www.epidemiolog.net/epid168/labs/AnalyticStudExerInstGuid2000.pdf


  • Login