Chpetwr two Health Survey for - (2).pdf

Health and Nutrition Survey

1. By:Dr.KedirN.(AssistantProfessor)
1
Survey and surveillance
September, 2025
E-mail:[email protected]

2. 2
1.Whatisstudydesign
2.Discusaboutobservational(casereport,caseseries,
ecological,crosssectional,casecontrolandcohort)
andexperimentalstudydesign,includingthestep
,advantageanddisadvantageofeachstudydesign
Discuss in group and share your idea

3. 3
Introduction

4. 4
Studydesignis
▪frameworkthatguideshowtoconducteachstep/stage
ofresearch
▪alogicalmodelthatguidestheinvestigatorinthe
variousstagesoftheresearch.
▪aspecificplanorprotocolforconductingthestudy,
whichallowstheinvestigatortotranslatethe
conceptualhypothesisintoanoperationalone.
▪Itisthe‘blueprint’ofresearchthatlaysout
Introduction

5. Epidemiological design
10/10/2025

6. 6
❑Choosingtypeofstudydesigndependson:
▪Whatistheresearchquestion/objective
▪Timeavailableforstudy
▪Resourcesavailableforthestudy
▪Typeofoutcomeofinterest
▪Qualityofdatafromvarioussources
Epidemiological study design

7. 7
•NohumaninterventioninvolvedinAssigningstudygroups;
simplyobservethe relationship betweenexposureanddisease
•Subjecttomanypotentialbiases,butbycarefuldesignand
analysis,manyof thesebiasescanbeminimized.
•Examplesofobservationalstudies:comparativecross-sectional,
cohortand case-controlstudies.
Observational study designs

8. 8
Investigatorobservesthenaturalcourseofevents
–Documentswhoisexposedornon-exposed
–Documentswhohasorhasnotdevelopedthe
outcomeofinterest
Observational study designs

9. 9
•Ininterventionstudies,theresearchermanipulates
asituationandmeasurestheeffectsofthis
manipulation.
•Theeffectsofaninterventionaremeasuredby
comparingtheoutcomeintheexperimentalgroup
withthatinacontrolgroup
•Usually(butnotalways)twogroupsarecompared,
onegroupinwhichtheinterventiontakesplace
(e.g.treatmentwithacertaindrug)andanother
groupthatremains‘untouched’(e.g.treatment
withaplacebo).
Experimental Studies

10. 10
▪Investigatordetermineswhoisexposed,ideally
usingrandommethods
▪Investigatorallocatestheexposureandfollowsfor
anoutcome
▪Typesofinterventionalstudiesinclude
•RandomizedClinicalTrials
•FieldTrials
•CommunityInterventionTrials
•Quasi-experimentalStudies
Intervention studies

11. Case control vs cohort

12. 12
Definition (what) survey

13. 13
•Gatheringinformationonspecifictopics
•Maybeusedtodescribeelementsofaspecificgrouporgeneralizetoa
largerpopulation
•Maystudyrelationshipsbetween/amongvariables
•Surveyresearchisprobablythebestmethodavailabletoresearcherwho
isinterestedincollectingoriginaldatafordescribingapopulationtoo
largetoobservedirectly.
Survey

14. 14
•Asurveymaybedefinedasthecollectionofinformationfromallindividuals
orasampleofindividualschosentoberepresentativeofthepopulation from
whichtheyaredrawn.
•Asurveyisatechniquebasedonsamplingmethodsbymeansofwhichwe try
toobtainspecificinformationfrompartofthepopulationliabletobe
consideredasrepresentativeofthewhole.
•Surveysaremadeatagivenmoment,inaspecificterritory;sporadically
Survey

15. 15
▪First to estimate certain population parameters (eg.prevalence )
▪Assess association of factors
▪Associations with service use
▪To generate and test hypothesis
Objectives of survey study

16. 16
▪It is carried out in natural settings
▪Random probability sampling is often easier to conduct than for
experimental studies
▪This allows statistical inferences to be made in relation to the
broader population of interest
▪Thus, allows generalizations
▪Increases the external validity of the study
Major advantages of survey

17. 17
▪Consider a sample
▪Construct a questionnaire to elicit information
▪Administer questionnaire to a sample of study subjects:
▪Face to face interviews
▪Self administered formats
▪Mailed questionnaires
▪Responses coded into a standardized form
▪Coded responses analized
▪Standardized responses subjected to aggregated analysis to provide
description of the sample
▪The descriptive conclusions then generalized to the population from
which the sample is selected
Surveys examine certain characteristics and proceed as follows:

18. 18
▪Toprioritizehealthproblemsandplaninterventions
▪Assesstheprevalenceofahealthproblem
▪Assesstheprevalenceofknownriskorotherfactors
▪Riskfactors:e.g.watercontact,smoking,unprotectedsex
▪Demographic:e.g.age,sex,family,fertility
▪Socio-economicposition:e.g.educationalattainment,employment,
income,wealth,
▪Opinionsandattitudes:politics,commercials,etc
Use of survey

19. 19
▪Objectives
▪Methodology
▪Time involved to conduct research
▪Survey research tool
Types of survey research

20. 20
1.ExploratorySurveyResearch
▪Aimedatfindingoutmoreabouttheresearchcontext
▪Thesurveyresearchpaysattentiontodiscoveringnewideasandinsightsabout
theresearchsubject(s)orcontexts
▪Usuallymadeupofopen-endedquestionsthatallowrespondentstofully
communicatetheirthoughtsandvaryingperspectivesonthesubjectmatter
▪Inmanycases,systematicinvestigationkicksoffwithanexploratoryresearch
survey
Research Based on Objective

21. 21
▪Referredtoascausalsurveyresearchbecauseitpaysattentiontothe
causativerelationshipbetweenthevariablesinthesurveyresearch.
▪predictivesurveyresearchpaysattentiontoexistingpatternstoexplainthe
relationshipbetweentwovariables.
▪allowyoutodeterminethenatureoftherelationshipbetweenthecausal
variablesandtheeffecttobepredicted--causeandeffect.
2. Predictive Survey Research

22. 22
•Islargelyobservational
•Itisidealforquantitativeresearchbecauseithelpsyoutogather
numericdata.
•Describehealthandhealthrelatedeventsintermsoftime,place,
andperson
3. Descriptive Survey Research

23. 23
1.QuantitativeResearch
•Isacommonresearchmethodthatisusedtogathernumericaldatain
a systematicinvestigation.
2.QualitativeResearch
•Thisisamethodofsystematicinvestigationthatisusedtocollect
non-numericaldatafromresearchparticipants.
•Qualitativeresearchmethodsincludeone-on-oneinterviews,
observation, casestudies,andfocusgroups.
Based on Methodology

24. 24
1.CrosssectionalSurvey
•Dataarecollectedatonepointintimefromasampleselectedto
representa largerpopulation
•Cross-sectionalsurveyresearchcaneitherbedescriptiveoranalytical
•Bothexposureandoutcomesassessedsimultaneously
•Aimsstudyassociationsb/nvariables
Based on time

25. 25
•Involvesconductingsurveyresearchoveracontinuumoftimeandspread across
yearsanddecades.
•Aimstoinvestigatecausalassociationsb/nvariables
a.Trend:Surveysofsamplepopulationatdifferentpointsintime
b.Cohort:Studyofsamepopulationeachtimedataare
collected,althoughsamplesstudiedmaybedifferent
c.Panel:Collectionofdataatvarioustimepointswiththesamesample of
respondents.
2.Longitudinal survey

26. 26
1.Panelsurvey:followupofthesamepopulation;
•Sometimereferredas ‘naturalexperiments’thesample ‘naturally’
dividedintocasesandcontrols
•Incidenceratescanbecalculatedinexposedandnonexposed groups
•Asampleofdefinedpopulationisfollowedupatmorethan
onepointintimeandchangesarerecordedatintervals
•Thesamesampleintervieweduntilthestudyterminatesorthe sample
leavethestudy(i.e.persontime)
Panel survey

27. 27
▪Carefuldefinitionofthegroup
▪Carefulselectionofvariableformeasurement
▪Datacollectedatfrequenttimeinterval
▪Clearrationaletosupportthetimingofrepeatedsurveypoint
(eg.atperiod whenchangesanticipated)
▪Memorybiasasretrospectivestudies
▪Responserateneedstobehigh
Points to be considered:

28. 28
•Trend survey : different samples at each data collection period
•Aimstosamplearepresentativesampleofthepopulationof
interestatthe outsetofthestudy
•Inordertotakeaccountofchangesinthewiderpopulationovertime
•Drawanewsampleateachfuturemeasurementpoint
•Usedtoidentifysamplememberswithdifferentlevelsofexposure to
apotential diseaseandtoenableincidenceratestobecalculated
•i.e.Thenumberofnewcasesofdiseaseoccurring inadefinedtime
period
Trend survey

29. 29
•Datacanbecollectedfromrecordsaboutstudysamplefrommore
thanonetimeperiodinthepast
•example,analysisofpatient'srecordsrelatingtomorethanone
periodinthepast
Retrospective longitudinal survey

30. 30
▪Itisexpensive–ittakesalongtimeandresources
▪Computing–mergingofdatabasesfordifferentfollowupwaves
▪Sampleattrition(i.e.panelsurvey)
▪Itisoftendifficulttouselongitudinaldatatosuggestacausal relationship
b/navariableandadisease
▪Thelongonsetfromexposurethedevelopmentofmostdiseasesandthe
difficulties intiming the successivefollow-upwaves
▪Theyareoftenfacedtheproblemofreversecausation(i.ethecausal
directionistheoppositetothathypothesized)
▪Associations are alsodifficulttointerpret owingtothemultifactorialnatureof
manydisease
Challenges of longitudinal studies

31. 31
▪Changeofvariationofinterestovertime
▪Populationandindividuallevel
▪Separatelyestimatethecross-sectionaleffectand longitudinaleffect
▪Morepowerfultodetectionanassociationofinterestcomparetocross sectional
studies
▪Allowtostudythewithin-subjectandbetween-subjectvariations
▪Providesmoreevidenceforpossiblecausalinterpretation
Advantages of longitudinal

32. 32
•Interview Surveys
•Telephone Surveys
•Online Surveys
•Mail surveys
Based on survey tool

33. 33
Research question (why)

34. 34
Cont.…

35. 35
Other data collection method

36. 36

37. 37
Selected Survey Resources

38. 38
Survey Methodology

39. 39
Cornerstone of survey Research

40. 40
Coverage error /defining population

41. 41
Sampling error –assessing sample representativeness

42. 42
Non response error –compare target and respondent
sample

43. 43
Mode of survey administration

44. 44
Choice of mode –consideration

45. 45
Mode of collection ,face to face

46. 46
Mode of collection ,telephone

47. 47
Measurement error –Asses accuracy and validity of
response

48. 48
Cont.…,

49. 49
Asking Good Questions

50. 50
Asking Good Questions

51. 51
Scoring -Scaling

52. 52
Scoring Issue( Likert type scale )

53. 53
Middle or Neutral scale point

54. 54
Type of question and items

55. 55
Survey Methods

56. 56
Step1.Definethepopulationandsample
•Researchquestionandpopulation
Step2.Decideonthetypeofsurvey
•Questionary,interview
Step3.Designsurveyquestion
•Type,contents,phrasing
How to conduct survey research

57. 57
Step4.Distributesurveyandcollectresponse
•When,where,howmanyresponses
Step5.Analyzesurvey
•Cleanincompleteresponse,staticalanalysis
Step6.Writeupsummeryresult
How to conduct survey research

58. 58
•Bothexposureanddiseaseoutcomearedetermined
simultaneouslyforeachstudysubjects
•Examinetherelationshipbetweendiseases/otherhealth
relatedcharacteristicsandothervariablesofinterestasthey
existinadefinedpopulationatoneparticulartime
•Populationsarecommonlyselectedwithoutregardtoexposure
ordiseasestatus
Cross sectional study (Survey)

59. 59
•Examinetherelationshipbetweendiseases/otherhealthrelated
characteristicsandothervariablesofinterestastheyexistina
definedpopulationatoneparticulartime
•Populationsarecommonlyselectedwithoutregardtoexposure
ordiseasestatus
•Oneofitsmajoradvantagesitisbasedonsampleofgeneral
population
•Thusitisgeneralizabletothepopulation
Cross sectional study (Survey)

60. 60
•Usuallymeasurediseaseprevalence in relation to exposure prevalence
i.e.,currentdiseasestatusisusuallyexaminedinrelationtocurrentexposure
level
•Itisalsopossibletoexaminediseaseprevalenceinrelationtopast exposureif
thedatesofexposureareascertained
Crosssectionalstudiesarecarriedoutfor:
•Publichealthplanning
•Etiologicresearch
•Itislessusefulinstudyingdiseasecausation
•Itismoreimportantinpublichealthplanningandevaluation
Cross sectional study (Survey)

61. 61
•dataiscollected atonepoint intimeand
•units ofanalysisareindividuals
•Cross-sectionalstudycanhavedescriptiveoranalyticpurposes
accordingtoitspurpose
•Descriptivecross-sectional:todescribefrequency/prevalenceor
distribution
•Analytic/comparativecross-sectional:toidentifydeterminant
factorsbyassessing presenceassociationbetweenexposureand
outcome
Peculiar characteristics

62. 62
•Iftheinformationcollectedispurelyofadescriptivenature,notinvolvingthe
comparisonof
•groups formed onthe basisof exposure or outcomestatus,thenthisisa
descriptive cross-sectionalstudy.
•Collectednumber ofcasesandnumber oftotalpopulation
•Conduct:Identifytargetpopulation
•Determinesamplesizeusingsinglepopulationestimationformula
•Drawrepresentativesample
•Assesspresenceofthecondition
•AnalyzedatatodetermineprevalencealongwithitsCI
Descriptive cross-sectional studies

63. 63
•Forassessingburdenofadisease:Diseaseprevalencesurveyand
Mortality survey
•Forassessingprevalenceofriskfactorsforadiseaselikesmoking,
obesity,low fruitandvegetableintake…
•ToassessSESandhealthrelatedknowledge,attitudeand
practiceofa population
•Toevaluatecoverageofinterventionslikevaccination
•Forassessmentofhealthserviceutilization
Application of descriptive cross-sectional studies

64. 64
▪Researchquestionsusuallyhavethefollowinggeneralforms:
–“IsFactorAassociatedwithFactorB?”
–"WhatistheprevalenceofDiseaseXorFactorYinagivenpopulation?“
–"HowmanypeopleinthepopulationhaveDiseaseXorFactorY?"
Application of descriptive cross-sectional studies

65. 65
•Ifdataarecollectedbothonexposuresandoutcomesofinterest,and
•Ifthedataareanalyzedsoastodemonstratedifferenceseitherbetweenexposed
andnon-exposedgroups,withrespecttotheoutcome,orbetweenthosewiththe
outcomeandthosewithouttheoutcome,withrespecttotheexposure,thenthis
isananalyticalcross-sectionalstudy.
•Comparativecross-sectionalstudies:Dependingonthepurposeofagiven
study,across-sectionalsurveycouldhaveananalyticalcomponent.
Analytic /comparative cross-sectional studies

66. 66
•Definedpopulationanddeterminethepresenceorabsenceofexposureand
presenceorabsenceofdiseaseforeachindividual
•Currentdiseasestatusisusuallyexaminedinrelationtocurrentexposurelevel
•Itisalsopossibletoexaminediseaseprevalenceinrelationtopastexposureif
thedates ofexposureareascertained
•Eachsuchsubjectthencanbecategorizedintooneofthefourpossible
subgroups
Analytic /comparative cross-sectional studies

67. 67
Design of Cross-sectional Studies

68. 68
•Conduct
•Identifytargetpopulation
•Determinesampleusingtwoproportionestimationformula
•Drawrepresentativesample
•Assessbothexposureandoutcomestatussimultaneously
•AnalyzedatatoassessassociationusingPR(PrevalenceRatio)orOR
Analytic /comparative cross-sectional studies

69. 69
•Sinceexposureanddiseasestatusisassessedatasinglepointintime,temporal
relationship betweenexposureanddiseasecannotbeclearlydetermined
•Studyprevalentcasesratherthanincidentcases
•Thepersonmighthavechangedthebehaviorthatresultedtothedisease
•Prevalentcasesrepresentsurvivorswhomaybeatypicalwithrespecttoexposure
status
•Incidence-prevalence/selectivesurvival/Neyman’sbias
•Therefore,identifyamixofriskfactors(incidence)andprognosticfactors
(duration)
Analytic /comparative cross-sectional studies

70. 70
•Define study question clearly
•Identify study population e.g.. school population
•If population small, study total population
•If the target population is large;
•Representative sample is selected
Initial steps

71. 71
•Populaton being large or dispersed
•Shortage of financial resources
•Limited time –results demanded urgently
•Shortage of trained manpower
•Consideration for a small population
•School children
•Workers in a small factory
•Inhabitants of a village
Factors dictating sample surveys:

72. 72
▪Example of cross-sectional study undertaken in Ethiopia
• Census –house hold level
• Ethiopian demographic and health survey(EDHS) house hold
level
• National immunization survey
Cont.…,

73. 73
•Once study population is defined -necessary data is collected.
•Presence of disease may be determined by:
•Interview of residents
•Examination of residents
•Reviewing of hospital records
•Contacting practising physicians
•Presence of exposure (to possible causative factors)should be
determined by appropriate tests
e.g.. Cigarette smoking, by interview or. air pollution levels -by
appropriate measuring devices.
Data collection in prevalence studies

74. 74
•EithercompareprevalencerateoftheoutcomeinexposedVs
non-exposed,or
•Compareprevalencerateoftheexposureinthosewithand
withouttheoutcome
•timingofthesubdivisionofthestudypopulationintocomparison
groupsdistinguishescrosssectionalstudiesfromother
observationalanalyticstudies
•Incohortandcasecontrolstudies,thistakesplacepriortothe
datacollectionprocess
•Inacrosssectionalstudy,thistakesplaceaftertheinformationhas
beencollected
Analysis

75. 75
Analysis
Measure of association is odds ratio

76. 76
•Measure of prevalence
•Describe the burden of disease
•Describe distribution (person, place, time)
•Migrant studies
•Gives clues on effect of genetic background and environmental
exposure on risk of disease
•KAP studies
•Purely descriptive without necessarily relating population
characteristics to any health outcome
Uses of cross-sectional studies:

77. 77
•Public Health planning
•Information used to plan service
•To assess utilization of health service
•To assess effectiveness of health service
•Studies of disease determinants
•Gives clue of aetiology pertaining to diseases of slow onset and
long duration
•Cross-sectional studies have certain advantages over case-control
and cohort studies
•They have as well obvious limitations
Uses of cross-sectional studies:

78. 78
1.Incrosssectionalstudyidentifyprevalentcasesratherthanincidentcases,
suchprevalentcasesmaynotberepresentativeofallcasesthatdevelopinthe
population
➢Prevalentcaseswillexcludethosewhodiedafterthediseasedevelopedbut
beforethestudywascarriedout
➢Thus,evenifanassociationofexposureanddiseaseisobserved,the
associationmaybewithsurvivalafterthediseaseratherthanwiththeriskof
developingthedisease
Points to be considered after checking the association
b/n exposure and outcome

79. 79
2.Thepresenceorabsenceofbothexposureanddiseaseis
determinedatthesametimeineachsubjectinthestudy
➢Itisoftennotpossibletoestablishatemporalrelationshipbetween
theexposureandtheonsetofdisease.i.e.,chickenoreggdilemma
Points to be considered after checking the association
b/n exposure and outcome

80. 80
•Length-biasedsampling:thecasesidentifiedwillover-representcasesoflong
duration(prevalentcases)andunderrepresentthosewithshortduration
•Thecasegroupwillhavemorethanitsfairshareofindividualswithdisease
oflongduration,b/cthosewhodieorrecoverquicklywillnotbeincluded
•Thiscanbiastheresultifdurationofdiseaseisassociatedwiththeexposure
understudy
Cont.…,

81. 81
▪Iftheexposuredoesnotalterdiseaseriskbutcausesthediseasetobe
mildandprolongedwhencontracted
▪Sothattheexposureispositivelyassociatedwithduration
▪Theprevalenceoftheexposurewillbeelevatedamongcases
▪Asaresult,theexposure-diseaseassociationwillbe
observedinacross-sectionalstudy,eventhoughexposurehasno
effectondiseaseriskandwouldbebeneficialifdiseaseoccurs
Cont.…,

82. 82
•Instudiesconductedinoccupationalsettings,suchstudiesmainlyincludeonly
currentandnotformerworkers,theresultsmaybeinfluencedbytheselective
departureofsickindividualsfromtheworkers
•Thosewhoremainemployedtendtobehealthierthanthosewholeave
employment
•Thisphenomenaisknownasthehealthyworkersurvivoreffect,generally
attenuatesanadverseeffectofanexposure
•Itmaynotshowstrongcause-effectrelationshipsifsamplesizeissmall
Cont.…,

83. 83
▪Gooddesignforhypothesisgeneration
▪Canestimateoverallandspecificdiseaseprevalence
▪Canestimateexposureproportionsinthepopulation–proportionof
cigarettessmokersinWoldiatown,latrineutilizationproportion
▪Canstudymultipleexposuresormultipleoutcomesordiseases-malaria
anddiarrheamorbidityVsproportionoflatrineandITNutilization
▪Relativelyeasy,quickandinexpensive
▪Bestsuitedtostudyingunchangedfactorsovertime(eyecolor,sex,blood-
type)–prevalenceofmalariabybloodtype
▪Oftengoodfirststeptoemployanalyticalstudydesigns
▪Highlygeneralizable
Advantages

84. 84
•Advantage of CS-studies
•Over case-control studies
•Generalizability, since based on a sample of the general population,
•Not just those seeking medical care, unlike in case-control studies
•Over cohort studies
•No need for large sample size
•No need for longer period of follow up
•No need to define incident cases
Advantages

85. 85
▪Impracticalforrarediseasesandrareexposure–becauseweneed
totakeverylargesamplesize
▪Notausefultypeofstudyforestablishingcausalrelationships–
chickenandeggdilemma
▪E.g.contraceptiveKnowledgeVsUse=whichcomesfirst
▪Missdiseasesstillinlatentperiod
▪Recallofpreviousexposuremaybedifficult
▪Potentialsurvivorbias
▪Potentialbiasinmeasuringexposure
Disadvantage

86. 86
Surveillance
Systematic, ongoing…
Collection
Analysis
Interpretation
Dissemination
…of health outcome data
Health action
investigation
control
prevention

87. •Physicians
•Laboratories
•STD clinics
•HC
•Community
health posts
Country Ministry of
health, CDC
analyze data using
statistical methods
•Public health officials
•Health directorates
•Health policy officials
Standardized data collection
Dissemination
to those who
need to know
Dissemination to those
who need to know
Change in public health
practice (vaccination,
reduction of risk factors,
medical intervention, etc.)
Public health planning
and intervention
Public health
evaluation
Surveillance Flow
87

88. 88
✓Dynamic
✓continuous process,
✓should be timely and
✓Purposeful
✓orientation for action
Generally, surveillance is:

89. 89
•Tobeabletoidentifydisease,injuries,hazardsandotherhealthrelated
factorsasearlyaspossible;predictionandearlydetectionofdisease
•Toprovidescientificbaselinedataforprioritysetting,planning,
implementationandevaluatingdiseasecontrolprogramforboth
communicableandnon-communicablehealthproblem
•Todefinethemagnitudeanddistributionofdiseasebytime,personand
placedistribution
Purpose of surveillance

90. 90
•Followsecular(longterm)trendofdisease
•Projectionoffuturetrend
•Generatehypothesis,stimulateresearch
-Interpretationofsurveillancedatamayalsoprovidethebasisforgenerating
hypothesesandstimulatingcommunityhealthresearch
Cont.…,

91. 91
•Passive
•Active
•Sentinel
•Rumour
•Syndromic
Types of surveillance

92. 92
•LeonGordis.Epidemiology,4thedition,2009
•KennethJ.Rothmanetal.ModernEpidemiology,3rdedition
•CharlesHetal.EpidemiologyinMedicineAnnBowling.Researchmethodsinhealth:
investigatinghealthandhealthservices,2ndedition2002
•MarkWoodward.Epidemiologystudydesignanddataanalysis,2dedition,2005
•JenniferL.kelsy,etal.methodsinObservationalEpidemiology,2ndedition,1996
•RichardA.Crosbyetal.Researchmethodsinhealthpromotion,2006
•RebeccaGKnnapandMClintonMillerIII.ClinicalepidemiologyandBiostatistics
•DavidE.LilienfeldandPaulD.Stolley.FoundationsofEpidemiology3rdedition
•HarveyMotulsky.IntuitiveBiostatistics,1995
References

93. 93