Research Methodology - Study Designs


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Research Methodology - Study Designs

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  • Welcome to Research Methodology 101. Today we would like to cover some basics concepts related to library research and also touch on a few practical matters such as putting research into practice into your library, your job. I believe that we all can agree—no matter what type of library we work in or what type of position we hold within that library—that accountability and assessment are two governing themes of the day. We are being asked to assess and be accountable for—our services, our programs—especially our instruction programs—our collections. At the same time, ACRL IS has recently revised the Research Agenda for Library Instruction and Information Literacy. This research agenda can serve to help guide instruction librarians in assessing what they’re doing and how well they’re doing it, and how students are and are not learning. In any sort of assessment, one does research. And research need not be a scary thing. A research project can be a lot of fun.
  • Note to self  use timer for activity. 2?3? minutes after reading the slide. Good. I can see that you all have some questions about these methodologies and that now you are all warmed up for this session. Let me give you our session overview. Right now we’re going to map out some research basics and then quickly list a few topic ideas that could work into a research project within your library. After that we’ll talk a bit about the technical stuff—the research methodologies themselves. We’ll give you definitions and examples of studies that have used these methodologies. Most, if not all, of these are mentioned in the bibliography. Next. we will discuss common pitfalls found in any research study. Then we want to talk about how you can get started on your research agenda, how you can put it all together in your library setting.
  • Hey there, does this list of steps sound familiar with all you instruction folk out there? Or any of you who have conducted a class session on research basics? Yes! It’s the same basic plan. It was when you were writing your first research paper in high school and college and it’s the same plan now. Finding the right topic can seem like a daunting task but we’ll show you some ways to make that step easier. After that you need to figure out just what your research focus really is, and that’s often done in the form of a question. Next, or even simultaneously, you should define your population of study. Students? Faculty? Users in your library? Which users? On to the next step of deciding your research design as well as deciding on your research instrument. You might ask yourself, “Am I going to conduct a survey? Via the web? E-mail? In person? Mail in? Will I interview people? Will I use a published measurement or scale? Will I do a pre and post test study?” Next you need to put your research plan into action by gathering your data set. Maybe you are collecting transaction logs from your web site or from your catalog or maybe you are doing classroom research so you are collecting data from your students over many semesters to do a learning outcomes assessment study. Next, you need to interpret what you have found. This step takes a little time and more than a lot of thought. Finally, you should write up your findings. Think of it as telling a story about what you did and what you found out. Simple? No? Fun? Sometimes~ Long term rewards? Priceless!
  • Research Methodology - Study Designs

    1. 1. Basic Statistics (FK6163) Principles of Research Methodology Study Designs A presentation by Assc. Prof. Dr Azmi Mohd Tamil, Department of Community Health, Faculty of Medicine, Universiti Kebangsaan Malaysia
    2. 2. Research1. A systematic & organised scientific process to find answers to the questions.2. Getting specific answers to specific questions.3. Involves data collection, analysis & interpretation.
    3. 3. Research ProcessProblem selectionLiterature reviewFormulation of research objectivesSelection of variablesSelection of the appropriate studydesignSampling of populationData collectionAnalysis of dataPresentation of findings
    4. 4. Identifying the appropriate study design Research Methodology
    6. 6. Comparison between different designs
    7. 7. The study design differs from one another by;Intervention – present/absentTemporal sequence – when is the riskfactor and outcome measured;– At the same time– Risk factor before, outcome later– Outcome first, then risk factor (retrospectively)Sampling methods
    8. 8. Difference Between Study DesignsStudy Design Intervention Temporal Sequence Sampling Risk Factor andCross Sectional Absent Yes Outcome at same time. Outcome first, then riskCase Control Absent Matching factor (retrospectively). Risk Factor first, thenCohort Absent Maybe Outcome.Clinical/ Intervene, then measure Present RandomisationCommunity Trial Outcome.
    9. 9. SAMPLINGThe process of selecting study subjects froma larger populationextent to which research findings can begeneralised to a larger populationto save time, money, efficiency and safety.PROBABLITY SAMPLING - equal chance to bechosen ex. simple random, systematic, stratified,multistage, clusterNON-PROBABILITY SAMPLING - convenience,quota, purposive.
    10. 10. POPULATION TO CHOOSE FOR THE SURVEYSELECT REPRESENTATIVE POPULATION? sampling methods - simple random sampling (may not be practical in national study) - stratified random sampling (in hetero/ stratum) - multistage sampling (national-state- district-sub district-village) - cluster sampling
    11. 11. Which design is appropriate for my study?
    12. 12. How to study the problems or prove the hypothesis?Select appropriate study design - Descriptive - case report, case series, ecological correlation - cross-sectional / survey - case-control - cohort - intervention - clinical trial/ community trial
    13. 13. Questions that need to be answered ?distribution of blindness - descriptive ?correlation between import of fruits and visual acuity among the population - ecological correlation ?prevalence of blindness, cataract or poor vision - cross-sectional/survey ?association between vit A def. and blindness - case-control
    14. 14. Questions that need to be answered ?incidence and relative risk of radiation cataract among radiographers- cohort ?therapy/preventive methods useful or effective , daily vit A supplementation to prevent xeropthalmia - intervention
    15. 15. CROSS-SECTIONAL STUDYAlso known as Prevalence Study or Survey.
    16. 16. Cross-Sectional StudyMeasures the relationship of variablesin a defined population at oneparticular timeBoth risk factors (exposure) anddisease outcome are observed at thesame (point in) time in a sample (orthe entire population) of subjects.
    17. 17. Exposure & OutcomeExposure Outcome Time Confounders
    18. 18. Cross-Sectional StudyRisk Factor Outcome Time ConfoundersBoth Risk Factor & Outcome measured at the same time.
    19. 19. Cross-Sectional Study Risk Factor -Race Outcome-Diabetes Mellitus Disease + (14%) Indians (15%) Disease - (86%) Sample ratio Disease + (8%) Others (85%) Disease - (92%)Time Both Risk Factor & Outcome measured at the same time.
    20. 20. RESEARCH QUESTIONSWhat is the nature / magnitude of theproblem?Who is affected?How do the affected people behave?What do they know, believe, thinkabout the problem?We know very little about theproblems and its possible causes.
    21. 21. CROSS-SECTIONAL SURVEYMAY BE REPEATED - tomeasure changes over timeLARGE SURVEY - limitedvariablesSMALL SURVEY - unlimited
    23. 23. COMPARATIVE CROSS- SECTIONAL STUDYAN ANALYTICAL STUDYattempts to establish causes or riskfactors for certain problems e.g.– obesity and IGT– level of cholesterol and CHD– betel leaves and NIDDM– milk consumption and IDDM
    24. 24. Comparative Cross- Sectional StudyBoth risk factor(s) and outcome weremeasured at the same point in time inthe selected sample or population.The sample may have been selected torepresent the population being studied.The selection or sampling method maybe random or not-random (refer tosampling method notes).
    25. 25. COMPARATIVE CROSS- SECTIONAL DESIGN disease present factor present disease presentPOPULATION factor absent disease absent factor present disease absent factor absent
    26. 26. HOW TO COMPARE?PREVALENCE OF DISEASE INDIFFERENT SUBGROUP– Rate of DM among obese vs rate of DM among normal BMIPRESENCE OF VARIABLES (ORABSENCE) IN DISEASE VS NON-DISEASE– Rate of contact with pigs among those afflicted with Nipah virus against those free from the disease.
    27. 27. COMPARE RATES Disease Rate of disease TOTAL among the + -Exposure exposed + A B A+B = A/(A+B) - C D C+D Rate of disease among the non- TOTAL A+C B+D N exposed = C/(C+D) Disease Prevalence =(A+C)/N
    28. 28. ADVANTAGEScheaper, easier and fastercan study associationable to generalise findings to thelarger population prevalence – for planning, measure burdenof disease, identify high risk population.As a baseline for future cohort study
    29. 29. DISADVANTAGESCan show association only but NOTCAUSATION – no temporal sequencesurvivors problems – only those whostill survive are studied, may miss thecontribution of those that already diedfrom the disease.not suitable for rare diseases, or inremission etc.possible biases - selection,misclassification
    31. 31. CASE CONTROL STUDY - CONCEPTcomparison of group of diseasedperson (cases) with another group ofnon-diseased person (control) for pastexposure to a suspected cause of thedisease.arises because of hypothesis that therisk factor (exposure) causes thedisease
    32. 32. Case-Control Study Exposure Outcome Look back in time Time ConfoundersStarts with Outcome, then trace the retrospective exposure
    33. 33. Case-Control Study Outcome-Cataract Risk Factor-Diabetes Mellitus DM + (50%) Cataract Sample DM - (50%) ratio (1:1) DM + (8%) Normal vision DM - (92%)Time Past Starts with Outcome, then trace the retrospective exposure
    35. 35. CASE SELECTIONDetermine clear and reproducibledefinitions of the health problems to bestudied (avoid misclassification bias)source of cases All persons with the disease seen inparticular facility(ies) in a specified periodof time. All persons with the disease found ingeneral population.Incidence cases (newly diagnosed cases)preferred
    36. 36. CHOICE OF CONTROLSControls should ideally be selected from thesame population gave rise to casesSimilar to cases in regard to past potentialexposureFree from study diseaseIf controls are patient with other diseasesthen select only diseases that are not knownto have relationship with factors understudy.
    37. 37. MATCHING to take account for potentially confounding variables type of matching : • Frequency matching : selection of controls with the same proportionate distribution of the particular variable as the cases. (eg. age and sex) •Individual matching : pairing the controls with the cases on some common variables such as age, sex and ethnic group.• Matched variables cannot be evaluated
    38. 38. ASSESSMENT OF EXPOSURE Exposure should be assessed by the same method for both cases and controls blinding methods of assessment : • available records - hospital, vital, employment •interview •self-administered questionnaire •direct measurement• Comparability of the accuracy and completeness of data
    39. 39. UNMATCHED CASE- CONTROL STUDY OUTCOME CASE CONTROLRI Exposed a bSKFAC NotTO exposed c dR Analysed using Chi-Square & Odds Ratio = ad/bc
    40. 40. MATCHED PAIR CASE- CONTROL STUDY CASES Exposed Not exposedCO Exposed a bN (both pairs exposed) ( pairs of controls exposed)TR NotO exposed c dL (pairs of cases exposed) (both pairs not exposed) Analysed using McNemar and Odds Ratio = c / b
    41. 41. ADVANTAGESable to study rare diseasescan explore multiple exposuresrelatively inexpensivecan calculate Odds Ratiocan support causation but not prove iteasy to get cases
    42. 42. DISADVANTAGESAffected by biases such as selectionbias, information bias, recall bias.Temporal relationship may not beclear.Inefficient for rare exposureCan study only one outcome at a timeCannot measure prevalence orincidence.
    43. 43. COHORT STUDY
    44. 44. COHORT STUDYBASIC CONCEPT Group or groups of individuals are studied over time as to onset of new cases of disease and factors associated with the onset of disease. Synonyms : incidence study, longitudinal study, prospective study.
    45. 45. Cohort Study Exposure Outcome Look forward in time Time ConfoundersStarts with Risk Factor, then measure the future Outcome
    47. 47. Cohort Study Risk Factor-Weight Outcome-Diabetes Mellitus DM + (32%) OverweightFree Sample DM - (68%)from ratioDM (1:1) DM + (7%) Normal DM - (93%) Time Future Starts with Risk Factor, then measure the future Outcome
    48. 48. THE PURPOSE OF COHORT STUDYTo identify risk factors for diseaseto identify protective factors againstdiseaseto identify prognostic factors foroutcome of diseaseto describe the natural history of diseaseto determine the number of new cases ina population over time for :planning acute care servicesassessing effectiveness of preventivemeasures
    49. 49. TYPE OF COHORT STUDYPROSPECTIVE COHORT STUDY: the cohort assembled at the start of thestudy, followed over time (into thefuture) to determine the incidence ofdiseaseHISTORICAL COHORT STUDY:the cohort assembled in terms of aparticular exposure in the past and arefollowed through existing records intothe future.
    50. 50. CLASSICAL VS DYNAMIC COHORTCLASSICAL OR CASE-NONCASE- cohorts are counted by person contribution overtime, the denominator for incidence rate is population at risk.DYNAMIC OR POPULATION TIME cohorts are counted by person-time contribution overtime, the denominator for incidence density is person-time at risk
    51. 51. RecruitmentThose recruited must be free from thedisease of interest at the beginning ofthe study.Those with sub-clinical presentations ofthe disease may miss from beingexcluded. This is one of the challenges.
    52. 52. SELECTION OF COHORTSSOURCES :- geographically defined groups- special resource groups -doctors,nurses, factory workers etc.- special exposure group - expose toradioactive, asbestos, benzene, hazeCOMPARISON GROUPS :- similar in all respects except exposure
    53. 53. Cohort DefinitionBoth groups (E+ & E-) must have equalchance of being followed up.Types of cohort;– Representative – low exposed subjects– Enriched – high exposed subjects– Specific group – occupational, institutional etc.
    54. 54. ASSESSMENT OFEXPOSURE AND OUTCOMEINFORMATION ON EXPOSURE: records, cohort members, medical examination and measures of the environmentINFORMATION ON OUTCOME periodic reexamination surveillance of deaths, hospitalization, clinic visits
    55. 55. Follow-upKeep participation at > 90%Must have equal ability to detect disease in allsubjects and all groups, with standardmeasurementActive vs Passive follow-upVerbal AutopsyBlinding of the assessorAssess both primary and secondary outcomes
    56. 56. COHORT STUDY Relative risk (risk ratio)A measure of how many times more likelyare exposed persons to get the diseaserelative to non-exposedUseful for causative associationsSize of RR does not necessarily indicatemagnitude of incidence rates in exposedand non-exposed groupsCompares the relative contributions of riskfactors no matter how much of the diseaseexists
    57. 57. Cohort Study: Basic Steps Total population/sample No disease (a) Disease (b) No exposure (c) Exposure (d) ExcludeDisease (e) No disease (f) Disease (g) No disease (h) Relative risk = Ie/Ie = (g/d)/(e/c) ranges from zero (strong negative association) to infinity (strong positive association)
    58. 58. Relative Risk Cohort Study OUTCOME Disease + Disease -RI Exposed a bSKFAC NotTO exposed c dR Relative Risk = (a/(a+b))/(c/(c+d))
    59. 59. AdvantagesAble to show causationAble to measure riskMay represent populationIf the exposure occurs rarely, thencohort is a good way to study theoutcome.Can directly measure incidence
    60. 60. DisadvantagesHigh cost, longer time & relativelymore difficult to execute.Many subjects lost to follow-up.Control subjects may end up beingexposed i.e. start smokingNot suitable for rare diseasesBiases – more scrutiny of the exposedgroup.
    61. 61. Clinical Trials
    62. 62. CLINICAL TRIALAny prospective controlled assessment of :1. A treatment method2. Diagnostic technique3. Preventive measuresCharacteristicsPROSPECTIVE – cohort or group of patients,followed over a period of time, evaluation ofoutcome.CONTROLLED – 2 or more groups of patients. Allgroups are comparable to one another with respect toall factors relevant to the outcome
    63. 63. Clinical Trial Intervention Outcome Look forward in time Time ConfoundersStarts with Intervention, then measure the future Outcome
    64. 64. Clinical Trial Intervention Outcome-Improved? Improved (75%) Fluoxetine Sample No improvement (25%)Depressedpatients ratio (1:1) Improved (70%) Sertraline No improvement (30%) Time Future Starts with Intervention, then measure the future Outcome
    66. 66. EXPERIMENTAL STUDY C+ T+ C- Study EligiblePopulation Participants C+ Selection T- Randomisation C- Future
    67. 67. SELECTION OF SUBJECTSNumber, sourcesInclusion criteria : age range, sex, weight,diagnostic criteria, informed consent,cooperationExclusion: lack of inclusion criteria,pregnancy or lactation, drug allergy, diseaseseverity, other disorders, requirement ofother drugs, unresponsive cases, mentalstatus.
    68. 68. RANDOMISATIONMethod for inducing comparability betweengroupsEnsures that characteristics known orunknown did not influence the treatmentassignedTreatment given to the patient/next patientto enter the trial is determined purely bychance, not by any characteristics of thepatient
    69. 69. RANDOMISATIONAllows the computation of the probabilitythat the groups differ for both known andunknown characteristics.Does not guarantee perfect comparabilityBetter than any known procedureEach patient enter the trial has an equalchance of receiving which ever therapy
    70. 70. COMPARISON GROUPTo allow the evaluation of the outcomesof interest in a comparable group ofpatients who received a standard orbest available relevant alternativetreatmentThe effect of treatment are compared tothe effects of a control treatment
    71. 71. COMPARABILITYThe patients should not differ in anycharacteristics, known or unknown,relevant to the outcomes of interestother than the treatment employed.
    72. 72. Parallel vs Crossover Start BStart A B A A B B AEnd A B End B A
    73. 73. Crossover DesignDisease under study must be chronicand treatable but not curableDisease must be stable over course ofstudyUpon analysis, must consider; Period effect Carryover/residual effect
    74. 74. ADMINISTRATION OF STUDYInstitutional review – ethical committeeInformed consentReceipt, distribution and storage ofinvestigational suppliesInstructions to recordersInstructions to subjectsAdverse reaction reportingMonitoringReporting results
    75. 75. PROCEDUREAssignment of subjects to treatmentsInterview and examinationsMethods of assessmentLab. StudiesTreatment schedules: number of units pervisit, rules fo changing dosage, compliancechecksAdverse reactions: definition and grading,inquiry, management.Drops out: definition, handling andrecording, terminating and extending study
    76. 76. BLINDINGSingle blind : either the patient or thephysician knows the treatment whichhas been assignedDouble blind: neither the patients northe physician are aware of the treatmentassignedTriple blind: even the statistician notaware of the assignment.
    77. 77. FOLLOW-UP SCHEDULEThe schedule of visitsThe duration of follow-upMeasurement and procedures to beconducted at each visitsIn multi-centre trial, the methodologyof all measurements and proceduresshould be specified thoroughly.
    78. 78. EXPERIMENTAL STUDYADVANTAGES DISADVANTAGES the best design to Exposed to biases determine causal – selection, association and – attrition, evaluate program – compliance and performance – contamination biases. ethical implications
    79. 79. COMMUNITY TRIALS1. All prophylactic vaccines, such as those againstmeasles and rubella (german measles), diphtheria, andpolio, were tested on populations of children to prove theirefficacy in preventing the diseases.2. Prophylaxis with drugs such as penicillin to preventepisodes of rheumatic fever or isoniazide hydrochloride(INH) in the prevention of active tuberculosis.3. Antihypertensive drugs for the reduction of bloodpressure and prevention of complications such as stroke.They were proven effective in clinical trial experiments.4. Testing various forms of health service delivery, suchas comparing family practitioner services with physicianspecialty services.5. Health effects of radiation following the atom bombexplosions of 1945, the famine in Africa of 1974, of loss ofjobs in the recession of 1980.
    80. 80. TERIMA KASIH