2014 DISEASE DETECTIVES 2014 DISEASE DETECTIVES (B,C)(B,C)

KAREN LANCOURNational Bio Rules National Bio Rules

Committee ChairmanCommittee Chairman

Event Rules – 201Event Rules – 20144

DISCLAIMERThis presentation was prepared using draft rules.  There may be some changes in the final copy of the rules.  The rules which will be in your Coaches Manual and Student Manuals will be the official rules.

Event Rules – 2014Event Rules – 2014 There is a three topic rotation for There is a three topic rotation for Disease Detectives: Disease Detectives: Environmental Environmental QualityQuality, , Population GrowthPopulation Growth, and , and Food Borne Illness – each on a two year – each on a two year rotation rotation

2014 2014 isis Environmental QualityEnvironmental QualityBE SURE TO CHECK THE 2014 EVENT RULES FOR EVENT PARAMETERS AND TOPICS FOR EACH COMPETITION LEVEL

TRAINING MATERIALSTRAINING MATERIALS

Training Power PointTraining Power Point – content overview – content overview Training Handout Training Handout - content information- content information Sample TournamentSample Tournament –– sample problems with keysample problems with key Event Supervisor GuideEvent Supervisor Guide – prep tips, event needs, – prep tips, event needs,

and scoring tips and scoring tips Internet ResourcesInternet Resources & Training Materials & Training Materials – on the – on the

Science Olympiad website at www.soinc.org Science Olympiad website at www.soinc.org under Event Information under Event Information

A Biology-Earth Science CD, a Disease Detectives CD and the Division B and Division C Test Packets are available from SO store at www.soinc.orgwww.soinc.org

On-line Text Books On-line Text Books Principles of Epidemiology 3Principles of Epidemiology 3rdrd edition from CDC edition from CDC

http://www.cdc.gov/osels/scientific_edu/SS1978/http://www.cdc.gov/osels/scientific_edu/SS1978/SS1978.pdSS1978.pdff

Epidemiology Basics published by the World Health Epidemiology Basics published by the World Health Organization Organization

http://whqlibdoc.who.int/publications/http://whqlibdoc.who.int/publications/2006/9241547073_eng.pd2006/9241547073_eng.pdff

Basic-Statistics-and-Epidemiology-a-Practical-GuideBasic-Statistics-and-Epidemiology-a-Practical-Guide http://www.scribd.com/doc/7885761/Basic-Statistics-and-http://www.scribd.com/doc/7885761/Basic-Statistics-and-Epidemiology-a-Practical-GuideEpidemiology-a-Practical-Guide

EpidemiologyEpidemiology 2014 focus is Environmental Causes of Health Problems2014 focus is Environmental Causes of Health Problems ContentContent

DefinitionsDefinitions of basic epidemiologic terms of basic epidemiologic terms CategoriesCategories of disease causing agents of disease causing agents ModesModes of disease spread of disease spread TriadsTriads of analysis (e.g., person/place/time & of analysis (e.g., person/place/time &

agent/host/environmentagent/host/environment Basis for taking actionBasis for taking action to control and prevent the to control and prevent the

spread of diseasespread of disease Process SkillsProcess Skills – – hypothesis, observations, inferences, hypothesis, observations, inferences,

predictions, variable analysis, data analysis, predictions, variable analysis, data analysis, calculations, and conclusionscalculations, and conclusions

Event ParametersEvent Parameters – – be sure to check the rules for be sure to check the rules for resources allowedresources allowed

Some Environmental Some Environmental Causes of Health Causes of Health Problems Problems

Air pollution , Smoking, Inducers of AsthmaAir pollution , Smoking, Inducers of Asthma Flooding health problems, Drought Flooding health problems, Drought

problems problems Extreme heat, UV exposure Extreme heat, UV exposure Lead contamination, Pesticides, Chemical Lead contamination, Pesticides, Chemical

Spills Spills Water pollutants, Heavy metals Water pollutants, Heavy metals Ventilation pollutants Ventilation pollutants Noise induced hearing lossNoise induced hearing loss Waste and toxic substance Waste and toxic substance Food contamination Food contamination

Event MakeupEvent Makeup Format and materialFormat and material of the Division B of the Division B

and C event is similar except that the and C event is similar except that the level of reasoning and math skills level of reasoning and math skills should be consistent with the grade should be consistent with the grade level. level. Div. C will include some statisticsDiv. C will include some statistics

DifferencesDifferences between the two levels between the two levels should be reflected in both the type of should be reflected in both the type of questions asked and the scoring rubrics.questions asked and the scoring rubrics.

EPIDEMIOLOGYEPIDEMIOLOGY Health of populations Health of populations instead of individualsinstead of individuals Scientific method Scientific method – organized problem solving– organized problem solving Distribution and determinants of disease Distribution and determinants of disease in in

human populationshuman populations Prevent and control Prevent and control those diseasesthose diseases Health-related eventsHealth-related events:

chronic diseaseschronic diseases environmental problems environmental problems behavioral problemsbehavioral problems injuries injuries infectious diseasesinfectious diseases

TypesTypes of skills neededof skills needed Recognize Recognize risk factorsrisk factors for health problems for health problems Know the Know the components of the scientific methodcomponents of the scientific method

used in investigating a disease outbreak to used in investigating a disease outbreak to real-life situations affecting healthreal-life situations affecting health

Understand and interpret the Understand and interpret the basic concepts basic concepts of mathematicsof mathematics (rates & proportions as attack (rates & proportions as attack rate, relative risk & odds ratio) used to assess rate, relative risk & odds ratio) used to assess health risks health risks

Recognize an epidemiological Recognize an epidemiological case definitioncase definition Know the different Know the different types of study designstypes of study designs

used by epidemiologists and be able to used by epidemiologists and be able to recognize them from written accountsrecognize them from written accounts

Scientific Method as Scientific Method as related to Disease related to Disease Detectives Detectives

Obtain Background InformationObtain Background Information Define the ProblemDefine the Problem Formulate HypothesisFormulate Hypothesis Develop a Study to Test the HypothesisDevelop a Study to Test the Hypothesis Collect Data and ObservationsCollect Data and Observations Evaluate Results Evaluate Results Determine if Hypothesis is true/modifyDetermine if Hypothesis is true/modify Formulate ConclusionsFormulate Conclusions Report ResultsReport Results Compare these steps to 10 Steps in Compare these steps to 10 Steps in

Outbreak InvestigationOutbreak Investigation

Outbreak Outbreak InvestigationInvestigation10 Steps 10 Steps

Outbreak Outbreak – (localized epidemic) – more cases of a – (localized epidemic) – more cases of a particular disease than expected in a given area or among particular disease than expected in a given area or among a specialized group of people over a particular period of a specialized group of people over a particular period of time.time.

EpidemicEpidemic – large numbers of people over a wide – large numbers of people over a wide geographic area affected. geographic area affected.

PandemicPandemic -An-An epidemic epidemic occurring over a very wide area occurring over a very wide area (several countries or continents) and usually affecting a (several countries or continents) and usually affecting a largelarge proportion proportion of the population. of the population.

ClusterCluster –an aggregation of cases over a particular period –an aggregation of cases over a particular period esp. cancer & birth defects closely grouped in time and esp. cancer & birth defects closely grouped in time and space regardless of whether the number is more than the space regardless of whether the number is more than the expected number. (often the expected number of cases is expected number. (often the expected number of cases is not known.)not known.)

Public Health SurveillancePublic Health Surveillance - - the systematic collection, the systematic collection, analysis, interpretation, and dissemination of health data analysis, interpretation, and dissemination of health data to gain knowledge of the pattern of disease occurrence in to gain knowledge of the pattern of disease occurrence in order to control and prevent disease in the community.order to control and prevent disease in the community.

Step 1: Prepare for Field Step 1: Prepare for Field WorkWork

1.1. Research, supplies & equipment Research, supplies & equipment – research– research the disease or situation and gather the disease or situation and gather

needed needed supplies & equipment to conduct the supplies & equipment to conduct the

investigationinvestigation 2.2. Administrative arrangements Administrative arrangements – make – make

official administrative and personal travel official administrative and personal travel arrangementsarrangements

3.3. Local contacts Local contacts - follow protocol- follow protocol

Step 2: Establish the Step 2: Establish the Existence of an OutbreakExistence of an Outbreak

1.. Expected # of cases for area Expected # of cases for area – use records – use records as health dept., hospital records, death as health dept., hospital records, death records, physician records, doctor survey records, physician records, doctor survey to determine expected # for the area in a to determine expected # for the area in a given timegiven time

2.2. Other factors in play Other factors in play – numbers may – numbers may exceed normal due to factors such as exceed normal due to factors such as betterbetter

reporting, seasonal fluctuations, reporting, seasonal fluctuations, population changespopulation changes

Step 3: Verify the Step 3: Verify the DiagnosisDiagnosis

1.1. Proper diagnosis Proper diagnosis - - verify the procedures used to verify the procedures used to diagnose the problem and check methods used for diagnose the problem and check methods used for identifying infectious and toxic chemical agentsidentifying infectious and toxic chemical agents

2.2. Not lab error Not lab error – – be sure that the increase number of be sure that the increase number of cases are not due to experimental errorcases are not due to experimental error

3.3. Commonality Commonality – – interview several persons who interview several persons who became ill to gain insight concerning possible became ill to gain insight concerning possible cause, source, and spread of disease or problemcause, source, and spread of disease or problem

Step 4: Define and Identify Step 4: Define and Identify CasesCases

Case definitionCase definition – – establish with the 4 establish with the 4 components or standard criteria for components or standard criteria for determining who has the disease or conditiondetermining who has the disease or condition a.a. Clinical informationClinical information – about the disease or – about the disease or condition condition b.b. Characteristics Characteristics - of the affected people- of the affected people c.c. Location or place Location or place - as specific as possible - as specific as possible as restaurant, county, or several specific as restaurant, county, or several specific areasareasdd. . Time sequence Time sequence - specific time during which - specific time during which the outbreak or condition occurredthe outbreak or condition occurred

Case Definition forCase Definition for Influenza-like (ILI) Influenza-like (ILI)

A case of influenza-like illness (ILI) or A case of influenza-like illness (ILI) or influenzainfluenza is defined as a person with is defined as a person with fever of 37.8°C (100°F) or greater fever of 37.8°C (100°F) or greater orally or 38.3°C (101°F) rectally PLUS orally or 38.3°C (101°F) rectally PLUS cough during the influenza season cough during the influenza season (October 1 through May 31). (October 1 through May 31).

A person with laboratory confirmed A person with laboratory confirmed influenzainfluenza is also considered a case is also considered a case even if the person does not have even if the person does not have cough and fevercough and fever

Identifying CasesIdentifying Cases

Identification of specific casesIdentification of specific cases – kind & number – – kind & number – count specific casescount specific cases

ConfirmedConfirmed – have diagnosis with case – have diagnosis with case definition plus lab verificationdefinition plus lab verification ProbableProbable – many factors point to diagnosis but – many factors point to diagnosis but may lack lab verificationmay lack lab verificationPossiblePossible – some factors point to diagnosis– some factors point to diagnosis

Note:Note: Initial reports may be only a small Initial reports may be only a small sampling of the total problem. Be sure to sampling of the total problem. Be sure to expand search to determine the true size and expand search to determine the true size and extent of the problemextent of the problem

Line Listing Line Listing

Line ListingLine Listing – chart of specific cases including – chart of specific cases including information about each caseinformation about each case

• Identifying informationIdentifying information - ID or case # - left column - ID or case # - left column + name or + name or initials initials

• Clinical informationClinical information – diagnosis, symptoms, lab – diagnosis, symptoms, lab results, hospital – death?results, hospital – death?

• DescriptiveDescriptive: : timetime – date & time of onset + date of – date & time of onset + date of reportreport

• DescriptiveDescriptive: : personperson – age, sex, occupation, other – age, sex, occupation, other characteristics characteristics

• Descriptive:Descriptive: placeplace – street, city or county + specific – street, city or county + specific sitesite

• Risk factors & possible causesRisk factors & possible causes – specific to – specific to situation (disease) and outbreak settingsituation (disease) and outbreak setting

Sample Line Listing Sample Line Listing

Sample Line ListingSample Line Listing from six case report forms on a wedding from six case report forms on a wedding reception outbreakreception outbreak

ID # Initials Date Diagnosis How Age Sex County Physician Wedding

of Onset Confirmed 1 KR 7/23 probable trichinosis Not done 29 M Columbia Goodman

Yes 2 DM 7/27 trichinosis Biopsy 33 M Columbia Baker

Yes 3 JG 8/14 probable trichinosis Not done 26 M Columbia Gibbs

Yes 4 RD 7/25 trichinosis Serologia 45 M King Webster

Yes 5 NT 8/4 trichinosis Not done 27 F Columbia Stanley

Yes 6 AM 8/11 R/Otrichinosis Pending 54 F Clayton Mason

Yes

Step 5: Describe in terms Step 5: Describe in terms of Time, Place and of Time, Place and Person TriadPerson Triad

TIMETIME – a histogram showing the course of the – a histogram showing the course of the disease or outbreak to identify the source of disease or outbreak to identify the source of the exposure the exposure Epidemic Curve or Epi curveEpidemic Curve or Epi curve (Begin early & update often) (Begin early & update often)

PLACE PLACE – geographic extent plus spot map of – geographic extent plus spot map of cases to identify groups specific to a location cases to identify groups specific to a location or environmental factorsor environmental factors

PERSON PERSON – identify the affected population by – identify the affected population by

type of person or by exposures as age, sex, type of person or by exposures as age, sex, high risk exposure as with AIDShigh risk exposure as with AIDS

EPI Curve (Epidemic EPI Curve (Epidemic Curve)Curve)

x axisx axis= units of time equal to 1/4 to 1/3 incubation time and= units of time equal to 1/4 to 1/3 incubation time and y axis y axis = # = # of casesof cases

Note:Note: a single point or source will have only one peak, a plateau will a single point or source will have only one peak, a plateau will show a continuous common source, several uniform peaks will show a continuous common source, several uniform peaks will indicate a propagated outbreak spread from person to personindicate a propagated outbreak spread from person to person

Types of Descriptive Types of Descriptive StudiesStudies

Types of Descriptive StudiesTypes of Descriptive Studies – Study the distribution of a – Study the distribution of a problem by cases or outcome, frequency in population, exposure, problem by cases or outcome, frequency in population, exposure, time pattern or environmental factor (Studies without a control time pattern or environmental factor (Studies without a control group can be used for descriptive purposes!)group can be used for descriptive purposes!)aa. . Case reportCase report//case seriescase series – case report = detail report of a single– case report = detail report of a single

patient from one or more doctors while case series =patient from one or more doctors while case series = characteristics of several patientscharacteristics of several patients

b.b. Correlative studiesCorrelative studies – correlates general characteristics of the– correlates general characteristics of the population with health problem frequency with several groupspopulation with health problem frequency with several groups during the same period of time during the same period of time

Time series analysisTime series analysis – correlate within the same – correlate within the same population population a different point in time a different point in time

Ecologic relationsEcologic relations – correlate relative to specific ecologic – correlate relative to specific ecologic factors as diet factors as diet

c.c. Cross sectionalCross sectional - a survey of a population where participants - a survey of a population where participants are are selected irrespective of exposure or disease statusselected irrespective of exposure or disease status

Step 6: Develop HypothesisStep 6: Develop Hypothesis(Agent/Host/Environment (Agent/Host/Environment triad)triad)

1. Agent /host /environmentAgent /host /environment = agent capable of = agent capable of causing disease & its source host or persons causing disease & its source host or persons susceptible to agent + environment allowing susceptible to agent + environment allowing them to get togetherthem to get together

Infectious GroupsInfectious Groups:: viruses, bacteria, viruses, bacteria, protistans (protozoa), fungi, animals (worms)protistans (protozoa), fungi, animals (worms)

2.2. TestableTestable – hypothesis must be in a form that – hypothesis must be in a form that is testableis testable

3.3. Current knowledge & backgroundCurrent knowledge & background – it should – it should be based upon current knowledge and be be based upon current knowledge and be updated or modified as new information is updated or modified as new information is uncovered!!!uncovered!!!

Step 7: Evaluate Hypothesis Step 7: Evaluate Hypothesis (Analytical Studies = Control (Analytical Studies = Control Group)Group)

1. Compare with established fact – these Compare with established fact – these are used when evidence is strong and are used when evidence is strong and clear cutclear cut

2.2. Observational StudiesObservational Studies: (Study : (Study determinants of health problems – determinants of health problems – how & why)how & why)CohortCohort – Based upon – Based upon exposure statusexposure status whether or not they have outcome whether or not they have outcome (illness) (illness) works forward from exposureworks forward from exposure Case-ControlCase-Control - Works - Works backward from backward from effect or illnesseffect or illness to suspected cause. to suspected cause.

3.3. Must have lab verification to validate Must have lab verification to validate hypothesishypothesis..

Cohort Study – Cohort Study – ExposureExposure

Both groups have a known Both groups have a known exposure and are checked for exposure and are checked for future outcomes or illness.future outcomes or illness.

retrospectiveretrospective: (historic cohort) : (historic cohort) starts at exposure in past & moves starts at exposure in past & moves forward to outcomeforward to outcome

prospectiveprospective: starts a present : starts a present exposure and moves forward in exposure and moves forward in time to outcometime to outcome

Sample Cohort Study Sample Cohort Study using 2 X 2 tableusing 2 X 2 table

400 people400 people attended a special awards attended a special awards dinnerdinner

Some persons became ill.Some persons became ill. The suspected The suspected culprit was the culprit was the potato saladpotato salad. The population . The population at the dinner was then surveyed to at the dinner was then surveyed to determine who became illdetermine who became ill..

Disease Yes Disease NoDisease Yes Disease No

Exposed (Ate salad)Exposed (Ate salad) 150 150 (a)(a) 30 30 (b)(b)

Unexposed(no salad)Unexposed(no salad) 50 50 (c)(c) 170 170 (d)(d)

Calculating Attack Rate & Calculating Attack Rate & Relative RiskRelative Risk

Disease Yes Disease NoDisease Yes Disease No Exposed (Ate salad)Exposed (Ate salad) 150 150 (a)(a) 30 30 (b)(b)Unexposed (no salad)Unexposed (no salad) 50 50 (c)(c) 170 170 (d)(d)

Attack rateAttack rate – the rate that a group – the rate that a group experienced an outcome or illness= number experienced an outcome or illness= number sick ÷ total in that group (Look for high sick ÷ total in that group (Look for high attack rate in exposed & low rate in attack rate in exposed & low rate in unexposed)unexposed)

exposedexposed = a ÷ (a+b) = 150 ÷ 180 == a ÷ (a+b) = 150 ÷ 180 = 80%80% unexposedunexposed = c ÷ (c + d) = 50 ÷ 220 == c ÷ (c + d) = 50 ÷ 220 = 20%20% Relative riskRelative risk == [a ÷ (a+b)] / [c ÷ (c+d)] = [a ÷ (a+b)] / [c ÷ (c+d)] = 80% ÷ 20% =80% ÷ 20% = 44

Interpreting Results of Interpreting Results of Cohort Study Cohort Study

Relative riskRelative risk estimates the extent of the estimates the extent of the association between anassociation between an exposure and a exposure and a disease. It estimates the likelihood of disease. It estimates the likelihood of developing the disease in the exposed group developing the disease in the exposed group as compared to the unexposed group.as compared to the unexposed group.

A relative risk >1.0A relative risk >1.0 indicates a positive indicates a positive association or an increased risk. This risk association or an increased risk. This risk increases in strength as the magnitude of increases in strength as the magnitude of the relative risk increases. the relative risk increases.

A relative risk = 1.0A relative risk = 1.0 indicates that the indicates that the incidence rates of disease in the exposed incidence rates of disease in the exposed group is equal to the incidence rates in group is equal to the incidence rates in unexposed group. Therefore the data does unexposed group. Therefore the data does not provide evidence for an not provide evidence for an association. association.

Relative riskRelative risk is not expressed in negative is not expressed in negative numbers.numbers.

Case ControlCase Control - - IllnessIllness

Works Works backward from effect or illnessbackward from effect or illness to to suspected cause. suspected cause.

Control groupControl group is a selected group who is a selected group who has similar characteristics to the sick has similar characteristics to the sick group but is not ill. group but is not ill.

They are then checked for similar They are then checked for similar exposures. exposures.

It is often hard to select the control It is often hard to select the control group for this type of study. group for this type of study.

Odds RatioOdds Ratio is calculated to evaluate the is calculated to evaluate the possible agents & vehicles of possible agents & vehicles of transmissiontransmission

Sample Case-Control Sample Case-Control StudyStudy

Sample: Sample: Several patients were diagnosed with Hepatitis A.Several patients were diagnosed with Hepatitis A.

• The local Restaurant A was thought to be the The local Restaurant A was thought to be the source of the infection.source of the infection.

• 40 case patients and a similar disease free group or 40 case patients and a similar disease free group or control were contacted to determine if they ate at control were contacted to determine if they ate at Restaurant A.Restaurant A.

2 X 2 table of data2 X 2 table of data

Ate Ate Case patients Case patients ControlsControls TotalTotalYesYes a =a = 3030 b =b = 36 36

6666NoNo c =c = 1010 d =d = 7070

8080Total Total 4040 106106 146 146

Calculating Odds Calculating Odds RatioRatio

2 X 2 table of data:

Ate Case patientsAte Case patients ControlsControls TotalTotalYesYes a =a = 3030 b =b = 3636 6666NoNo c =c = 1010 d =d = 7070 8080TotalTotal 4040 106106 146146 Odds RatioOdds Ratio = = Odds of exposure in casesOdds of exposure in cases = = a/ca/c = = a da d = = 30x7030x70 = = 5.85.8Odds of exposure in controls b/d b cOdds of exposure in controls b/d b c 36x1036x10

This means that people who This means that people who ate at ate at Restaurant ARestaurant A were were 5.8 5.8 times more likelytimes more likely to to develop hepatitis Adevelop hepatitis A than were than were people who people who did not eat theredid not eat there..

a = # of case patients exposed b = # of control exposeda = # of case patients exposed b = # of control exposedc = # of case patients unexposed d = # of control c = # of case patients unexposed d = # of control

unexposedunexposed

Step 8: Refine Step 8: Refine Hypothesis and do Hypothesis and do Additional StudiesAdditional Studies

1.. No confirmation of hypothesisNo confirmation of hypothesis - where - where analytical studies do not confirm analytical studies do not confirm hypothesis. May need to look for a hypothesis. May need to look for a new vehicle or mode of transmissionnew vehicle or mode of transmission

2.2. More specificMore specific – May need to be more – May need to be more specific in make up of case patients & specific in make up of case patients & controlscontrols

3.3. Verify with environmental/laboratory Verify with environmental/laboratory

studiesstudies - - verification with very control verification with very control conditions is very importantconditions is very important

Step 9: Implement Control Step 9: Implement Control and Preventative and Preventative MeasuresMeasures

1.. As soon as source is knownAs soon as source is known – people are sick – people are sick or hurting and need he must know agent & or hurting and need he must know agent & source of agent + susceptibility of host+ source of agent + susceptibility of host+ chain of transmissionchain of transmission

2.2. Aim at chain of agent-source-hostAim at chain of agent-source-host – break the – break the chain of transmission at any of its 3 pointschain of transmission at any of its 3 points

3.3. May interrupt transmission or exposureMay interrupt transmission or exposure – – withwith

vehicles as isolationvehicles as isolation4.4. May reduce susceptibilityMay reduce susceptibility – with – with

immunization,immunization, legal issues and/or educationlegal issues and/or education

Criteria to Draw Criteria to Draw Conclusions Conclusions

1. TemporalityTemporality – cause/exposure must precede – cause/exposure must precede effect/outcomeeffect/outcome

2.2. Consistency Consistency – observation of association must – observation of association must be repeatable in different populations at be repeatable in different populations at different timesdifferent times

3.3. Coherence, 1-1 relationshipCoherence, 1-1 relationship – exposure is – exposure is always associated with outcome/ outcome is always associated with outcome/ outcome is always caused by the specific exposurealways caused by the specific exposure

4.4. Strength of associationStrength of association – relationship is clear – relationship is clear and risk estimate is high and risk estimate is high

5.5. Biological plausibilityBiological plausibility – biological explanation – biological explanation makes sensemakes sense

6.6. Dose/response (biologic gradient)Dose/response (biologic gradient) – increasing – increasing risk is associated with increasing exposurerisk is associated with increasing exposure

Step 10: Communicate Step 10: Communicate

FindingsFindings

1. Oral briefingOral briefing – – inform local health inform local health officials or other need-to-know officials or other need-to-know groups as soon as information is groups as soon as information is availableavailable

2.2. Written reportWritten report – – usually done in usually done in scientific format for future scientific format for future reference, legal issues, and reference, legal issues, and education education

Potential Types of Error in Potential Types of Error in Data Collection - Division CData Collection - Division C

False Relationships False Relationships Random Error -Random Error - the divergence due the divergence due

to chance alone, of an observation on to chance alone, of an observation on sample from the true population value, sample from the true population value, leading to lack of precision in leading to lack of precision in measurement of association measurement of association

BiasBias - - systematic error systematic error in an in an epidemiologic study that results in an epidemiologic study that results in an incorrect estimation of the association incorrect estimation of the association between exposure and health-related between exposure and health-related eventevent

Potential Types of Error Potential Types of Error in Data Collection – Div. in Data Collection – Div. CC

Non-Causal Relationships Non-Causal Relationships ConfoundingConfounding – – occurs when the occurs when the

effects of two risk factors are mixed effects of two risk factors are mixed in the occurrence of the health-in the occurrence of the health-related event under study - when an related event under study - when an extraneous factor is related to both extraneous factor is related to both disease and exposure disease and exposure

Statistics for Division CStatistics for Division CDescriptive Descriptive EpidemiologyEpidemiology

MeanMean MedianMedian ModeMode VarianceVariance Standard deviationStandard deviation Standard errorStandard error Confidence intervals of means Confidence intervals of means

Statistics for Division CStatistics for Division CAnalytic Epidemiology Analytic Epidemiology

Z-testZ-test T-testT-test Paired T-testPaired T-test Chi-squareChi-square McNemar test for paired data McNemar test for paired data Fischers exact testFischers exact test Cochran Mantel-Haenszel Cochran Mantel-Haenszel

summary odds ratio summary odds ratio

Division B – Division B – Regional/State Regional/State

Modes of transmission Calculate health-related rates (attack, incidence,

prevalence, case fatality) Calculate a simple relative risk and describe what it

means Interpret epi curves, temporal patterns and other

simple graphic presentations of health data.. List, discuss and recognize examples of disease

causing agents (physical and biological) Demonstrate an understanding and ability to use

terms such as endemic, epidemic and pandemic; population versus sample, association versus cause.

Describe various types of prevention and control strategies (e.g. immunization, behavior change, etc) and situations where they might be used

Division B – National Division B – National

Understand how units affect the relative magnitude of a set of rates with different units.

Calculate appropriate measures of risk when given the study design

Complete tables when given all data needed to complete calculations.

Propose a reasonable intervention to a public health problem.

Recognize gaps in information

Division C – Division C – Regional/StateRegional/State

Recognize differences between study designs ,Types of Error, and do Statistical Analysis

Calculate measures of risk (e.g. relative risk or odds ratio) when given a description of the study design

Calculate measures based on data that is not given but that can be readily extracted.

Recognize how gaps in information influence the ability to extend conclusions to the general population.

Division C – National Division C – National Recognize unmentioned factors that may

influence results. Recognize Types of Error and do

Statistical Analysis Convert between rates with different

basic units (e.g. incidence per 10000 persons/year to incidence per 100 persons/week).

Propose a means to evaluate the effectiveness of an intervention or control program.