research-methodology-ppt

contentsIntroduction to researchDefinitions ResearchThesisDissertationWhy to do a researchCategories of researchResearch methods & research methodologyProcedural steps in researchResearch strategy epidemiologic studiesEthics in research

Introduction Investigation using scientific procedures, by searching again and again to find out the truth Research is the continual search for truth using the scientific method. It is the pursuit of the truth with the help of study, investigation, observation, comparison and/or experimentation.

definitionsResearch(WHO Health research methodology, 1992, a guide for training in research methods): Research is a quest for knowledge through diligent search or investigation or experimentation aimed at the discovery and interpretation of new knowledge. Scientific method is a systematic body of procedures and techniques applied in carrying out investigation or experimentation targeted at obtaining new knowledge. Here research and scientific methods may be considered a course of critical enquiry leading to discovery of facts or information which increases our understanding of human health and disease.

Thesis(according to Oxford English dictionary) A proposition laid down as a theme to be discussed and proved. A discussion to maintain and prove a thesis especially written or delivered by a candidate for university degree- Ph.D

Dissertation: Dissertation means “to discuss”.

It is an academic activity laid down by the university for the partial fulfillment of MDS degree.

It is an exercise to train a PG student to plan, execute, evaluate, write and report a scientific project.

It is an in-depth study of a particular topic which contributes new information and knowledge in the field

A formal, often lengthy treatise (a book or writing of some particular subject, one containing a methodical discussion or exposition of principles of subject) or discourse, especially one written by a candidate for a master’s degree.It is a pre-requisite or academic activity for acquiring a masters degree or doctorial.To find out the truth which is hidden and which has not been discovered yet.To contribute new knowledge to the existing one as the scientific knowledge develops in increments.As a profession to conduct research in various aspects.To solve an existing health problem.For thrill and enjoyment of discovering a new fact.

Categories of research Empirical researchandtheoretical research Basic researchandApplied researchEmpirical Observational research Experimental researchBasic or pure researchIt is usually considered to involve the search for knowledge without a defined goal of utility or specific purpose.Eg. The microbiologist, whose expertise is the identification of pathogenic micro organisms may conduct research in-vitro, in a laboratory on bacterial reproduction, growth and endotoxin production without any direct application to clinical dentistry. Probably, the researcher is interested in monitoring endotoxins produced over the life cycle of bacteria to determine a pathogenecity.

Applied researchIt is problem oriented and is directed towards a defined and purposeful end. Eg. An oral health researcher investigating the relationship between periodontal disease and myocardial infarction may use the findings of the microbiologist as a theoretical framework to test the relationship between bacterial endotoxins, periodontal disease and myocardial infarction in animal and then in human subjects

methods/ techniques that are used for conducting research are termed as research methods or research techniques.They fall into 3 groupsThose concerned with collection of dataThose statistical techniques which are used for establishing relationship between the data and the unknownThose methods which are used to evaluate the accuracy of the results obtained.

Research methodologyIt is a way to systematically solve the research problem.It is necessary for the researcher to design his methodology for his problem, as the same may differ from problem to problem i.e. Why a research study has been undertakenHow the research problem has been defined In what way and why the hypothesis has been formed

What data has been collectedWhat particular method has been adopted for collection of dataWhy a particular technique of data collection has been used And a host of similar questions are usually answered when we talk of research methodology, so that research results are capable of being evaluated either by the researcher himself or by others

Selection of problem for investigation-further explorationInexperienced-seek opinion –seniorConstructing –essential starting pointReview literatureModern electronic researchAbstract collection held on CD-ROMS-enables –key wordsMedline and psyclit databaseRole of systemic review grown recently-cochrane collaboration-reviews from volunteer researchers internationally adds them to a bank,which is open for inspection by interesting parties.

Specifying study designSelection of measures: many measure ,assessments Eg:self report rating scales for dental anxiety,observations,interviews,stand questionnaires simple rating scale can be given a no.1-strongly agree 2-agree 3-undecided 4-disagree 5-strongly disgreeMay not exist for the study ,this may necessiate the development of new scale. should possess Reliability and validity

Selection of sample:Sampling techniques-inorder to provide information ,can be generalised to cover the whole population.Writing a protocol: aims & objectives,method,materials,sample ,procedure

Ethical approvalPilot workMain studyAnalysis of resultsReport writingpublication

Research strategiesSelection of a research strategy is the core of a research design and is probably the single most Important decision the investigator has to make, i.e. whether to undertake a descriptive, an analytical or an experimental study.

Classification of Epidemiologic studies

Decscriptive studyConcerned with observing the distribution of disease or health related characteristics in human populationEg. Surveys.

Defining population:denominator

Defining the disease:operational definition.

Describing disease-time,place and personTime:Short term fluctuation:Common source epidemics-single,continuousPropagated epidemics-person to person transmission of infectious agent---epidemics of hepatitis A and poliomyelitisSlow or modern epidemics

Periodic fluctuations:Seasonal –communicable diseases like measles,varicella,malariaEg:upperResp tract infections inc during winter and GI inf in summerCyclic trends-measles-incidence every 2-3 yrsInfluenza occurs at intervals of 7-10 yrsLong term fluctuationChanges occur over long period of time,change in frequency encompassing sev decadesEg:CHD,diabetes,lung cancer shows upward trend in 50 decades and TB, typhoid downwardPlace distribution:Interanational-National-endemic disease like goitre,flourosisRural-urban-lung cancer,cardiovascular accidents-urbanLocal-spot maps (john snow –on epidemic of cholera)and shaded maps -study

Person distribution:age sexMeasurement of disease :morbidity and mortality indicatorsExpressed in terms of incidence and prevalenceComparing with known indices:comparision b/n different population and subgroups of same populn-clue to etiologyFormulation of hypothesis:relating to disease etiology specify-population,sp cause ,expected outcome,dose-response r/n,time-resp r/n.Eg:smoking of 30-40 cigarettes/day causes lung cancer in 10% of smokers after 20 yrs of exposure.Uses:magnitude and type of disease in communityClues to etiologycontributes to research

surveysSurveys are methods of scientific or systematic collection of data, compiling, presenting in order (useful manner), analysing and evaluating themThe focus of attention must be on the followingFormulating the objective of the study-obj describing what is to be measured,resourcesDesigning the method of data collection eg. Questionnaires, interviewing, examination of records or observationsSelecting the sample

Collection of data through questionnairesQuestionnaire is considered as the heart of survey operation. General form: It can be either structured or unstructured.May be either closed or open.Question sequence:The question sequence should be clearFirst few questions are particularly important in seeking the desired co-operation Questions related to personal character, wealth or memory of the respondent should be avoided as opening questions

Conducting examination:Obtaining approval from authoritiesBudgetingSchedulingEmergency care and refferal(diagnostic method)Validity and reliabilty of the data

Classification of study types-ADA(1970)typeI: complete examinationtypeII: limited examinationType III: inspectionType IV:screeningprocedures:tongue depressord) Analysing the datae)Drawing the conclusionf) Publishing the reports

Case study: it is an intensive investigation of a person, a family, a group, a social institution or an entire community in a natural settingCorrelational study: it is a descriptive research technique utilized to identify consistent relationship among variables

Analytical studySecond major typeSubject of interest –individual with in populationObject –not to formulate but test hypothesisCan determine:1.Statistical association between disease and suspected factors2.If exists--strength

Case control studies Design of a case-control studyTimeDirection of enquiryExposedCasesPopulationNot ExposedExposedControlsNot Exposed

Defining the cases and controls:Case: you have to decide a case before the start of the study. The case has to fit in to two criteria.Diagnostic criteria.Eligibility criteria. only newly diagnosed cases within a specified period of time than old cases

Selection of casesThe criteria for inclusion in the study must be clearly specified. Sources of cases:Hospitals General population

Controlsthey must be as similar to the cases as possible, except for the absence of the disease,which is under study.Selection of controlsCrucial step in case-control studiesControls must beBe similar to the cases except for the absence of the disease under studyEqual ratioSources of controlsHospitals:diff illnessRelativesNeighborhood controlsGeneral population

MatchingDefinition: the process by which we select controls in such a way that they are similar to cases with regard to certain pertinent selected variables, which are known to influence the out come of disease and which, if not adequately matched for comparability, could distort or confound the results.Example: age.Confounding factorOne which is associated both with exposure and disease; and is distributed unequally in study and control groupsAlthough associated with ‘exposure’ under investigation, it itself is a risk factor for the disease

Measurement of exposureExposure can be measured byInterviewsQuestionnairesBy studying past recordsExaminations Bias/ systematic error should be avoided while measuring the exposure

Analysis Involves two stepsExposure rates among cases and controlsEstimation of disease risk associated with exposure (odds ratio)

1. Exposure ratesA case control study of smoking and lung cancerExposure rate among cases= (a/a+c)100 = (33/35) 100 = 94.2 % Exposure rate among controls= (b/b+d)100 = (55/82) 100 = 67 %

2.Estimation of riskIncidence among exposed Relative risk = Incidence among non exposed Relative risk (RR) or Risk ratio = a/(a+b) / c/(c+d)

Odds ratio (cross product ratio)It is a key parameter in the analysis of case control studiesA measure of the strength of the association between risk factor and outcomeDerivation of odds ratio is based on 3 assumptionsDisease under investigation is a rare oneCases are representative of those with diseaseControls are representative of those without disease

Odds ratio = ad/bc = 33 X27/ 55X2 = 8.1Smokers have a risk of having lung cancer 8.1 times that of non smokers

Bias in case control studyBias due to confoundingMemory biasSelection biasBerksoniansbias:different rates of admission to hosp for people with diff diseaseInterviewer’s bias

advantages of …Relatively easy to carry outRapid and inexpensive (compared with cohort studies)Require comparatively few subjectssuitable to investigate rare diseases or diseasesabout which little is known. No risk to subjectsAllows the study of several different aetiological factors (e.g.,smoking, physical activity and personality characteristics inmyocardial infarction)No attrition problems, because case control studies do notrequire follow-up of individuals into the futureEthical problems minimal

Disadvantages of …High chances for biasValidation of information obtained is difficult or sometimes impossibleSelection of an appropriate control group may be difficultWe cannot measure incidence, and can only estimate the odds ratio but not relative riskNot suited to the evaluation of therapy or prophylaxis of a diseaseAnother major concern is the representativeness of cases and controls

Cohort studiesUsually undertaken to obtain additional evidence to refute or support the existence of an association between suspected cause and diseaseOther names Incidence studyForward looking studyLongitudinal studyProspective study

distinguishing Features of …Cohorts are identified prior to the appearance of the disease under investigationStudy groups are observed over a period of time to determine the frequency of diseaseThe study proceeds from cause to effect

Cohort is defined as a group of people who share a common characteristic or experience within a defined time period Eg, birth cohort,age cohorts, occupational cohorts, exposure to a drug cohorts, marriage cohort etc.The comparison group may be… the general population from which the cohort is drawn

Indications for …When there is a good evidence of an association between exposure and diseaseWhen the exposure is rare but the incidence of disease is high among exposed When the attrition can be minimisedWhen ample funds are available

Design of a cohort studyTimeDirection of enquiryScreening to exclude those with the conditionDevelopDiseaseaWith the characteristicSAMPLEDo not develop diseasePopulation free of conditionbTimeDevelopDiseasecWithout the characteristicdDo not develop disease

Considerations for selecting cohortsCohorts must be free from the disease under study both the groups should be equally susceptible to disease under studyBoth the groups should be comparable in respect of all possible variables, except the assumed risk factorsDiagnostic and eligibility criteria of the disease must be defined beforehand.Inclusion and exclusion criteria should be clearly stated before the commencement

Steps in …Selection of study subjectsObtaining data on exposureSelection of comparison groupsFollow upAnalysis

Selection of study subjectsCohorts can be selected fromGeneral populationSpecial groupsSelect groups (eg. Doctors, lawyers, teachers, etc.)Exposure groups

Obtaining data on exposureInformation can be obtained from Cohorts Review of recordsMedical examination or special testsEnvironmental surveysInformation about exposure should facilitate classification of cohort membersAccording to whether or not they were exposedAccording to the degree of exposure

Selection of comparison groupsInternal comparisons: no outside comparision group is requiredExternal comparisons: when degree of exposure is not available,ext cohort .eg:smokers and non smokers,radiologists and opthamologists.Comparison with general population:mortality experience of exposure group is compared with mortality experience of general populationin same geographic area

Follow upPeriodic medical examination of each memberReviewing physician and hospital recordsRoutine surveillence of morbidity and mortality recordsMailed questionnaires, telephone interviews, periodic home visits

Analysis Data is analysedinterms of Incidence rates of outcome among exposed and non-exposedEstimation of riskRelative riskAttributable risk

Incidence ratesIncidence can be measured directlyIncidence rate among smokers = 70/7000 = 10 per thousandIncidence rate among non-smokers= 3/3000 = 1 per 1000 P < 0.001

Relative riskRelative risThe ratio of incidence among exposed and incidence among non-exposedAlso called ‘risk ratio’RR=RR is the direct measure of strength of association between suspected cause and effect Incidence among exposedIncidence among non-exposed=10/1 = 10RR-i= no assossiationRR > 1= positive assossiation

Attributable riskIncident rate among exposed – incidence rate among non-exposedX 100Incident rate among exposed The difference in incidence rates between exposed and non-exposed groupsAlso called risk differenceof lung cancer was due to their smokingIt indicates to what extent disease can be attributed to the exposureSuggests the amount of disease that might be eliminated if the factor could be controlled(10-1/10) X 100 = 90%

Relative risk X Attributable risk Relative riskEtiological enquiriesLarger the RR, stronger the association between risk factor and outcomeDoes not reflect the potential public health importanceAttributable riskGives a better idea of the impact of a successful intervention might have in reducing the problem

Advantages of cohort studiesAllow the possibility of measuring directlythe relative risk of developing the condition for thosewho have the characteristic, compared to those who do notAllows for a conclusion of cause-effect relationshipBecause the presence or absence of the risk factor isrecorded before the disease occurs, there is no chanceof bias

Cohort studies are capable of identifying other diseases that may be related to the same risk factor.Unlike case-control studies, cohort studies provide thepossibility of estimating attributable risks, thus indicating the absolute magnitude of disease attributable to the risk factor.

Disadvantages of cohort studiesNot always feasible.Relatively inefficient for studying rare conditions.They are very costly in time, personnel, space and patientfollow-up.Sample sizes required for cohort studies are extremely large, especially for infrequent conditions; it is usually difficult to find and manage samples of this size.The most serious problem is that of attrition, which can affect the validity of the conclusion, if it renders the samples less representative, or if the people who become unavailable are different from those actually followed up. The higher the proportion lost (say beyond 10-15%) the more serious the potential bias.

There may also be attrition among investigators who maylose interest, leave for another job, or become involvedin another project.Over a long period, many changes may occur in theenvironment, among individuals or in the type ofintervention, and these may confuse the issue ofassociation and attributable risk.

Case control study cohort studyProceeds from effect to causeStarts with the diseaseTests whether the suspectedexposure occurs more frequentlyin those with the disease thanamong those without thedisease.Involves fewer number ofsubjectsYields relatively quick resultsSuitable for the study of rarediseasesGenerally yields only estimateof RR (odds ratio)Cannot yield information aboutdiseases other than thatselected for studyRelatively inexpensive Proceeds from "cause to effect".Starts with people exposed to risk factor or suspected cause.Tests whether disease occurs more frequently in those exposed, than in those not similarly exposed.Involves larger number of subjectsLong follow-up period often needed, involving delayed results.Inappropriate when the disease or exposure under investigation is rare.Yields incidence rates, RR as well as AR.Can yield information about more than one disease outcome.Expensive.

Experimental studiesStudy of epidemics among colonies of experimental animals such as rats and mice .AIMSTo provide scientific proofs of etiological factorsTo provide a method of measuring the effectiveness and efficiency of health services has all adv and disadv of cohort study and also ethics,cost and feasibilityAnimal studies: important applicationAdvantagesBred in lab,and can manipulated easilyThey multiply rapidly Disadvantages:Not all human diseases can be reprodeucedAll conclusions – not applicable

Human studies:To investigate disease etiology and to evaluate the preventive ,therapeutic measures1747-john lind-scurvy1796-Edward Jennar-cowpoxEthical and logistic considerations,benefits weighed againsts the risks involvedVolunteers –made fully aware of the experimentWHO (1980)-strict code of practice

Experimental studiesRandomised controlled trialsNon-randomized trialsRandomised controlled trials:Involves some action,intervention or manipulation such as deliberate application or withdrawl of suspected cause.Drawing up a protocalSelecting reference and experimental populationRandomization Blinding Manipulation or interventionFollow- upAssessment of outcome

Select population (Reference or target population)Select suitable sample (Experimental or study population)DEsiGN oF aNRCT-DBSelection by defined criteriaPotential participants (Meet selection criteria)Non-participants(do not meet selection criteria)Non-participants(do not give consent)Invitation to participateParticipantsRandomization & double blindingExperimental groupManipulation,Follow up& Assessment Control group

Positive results: benefit of exp measure----reduced incidence or severity of disease or other appropriate outcomes of study.Negative results: severity and frequency of side effects and complications ,if any deathBlinding:Randomization cannot guard against these sorts of bias nor the size of the sample.the technique known as blinding is adopted which can be done inSingle blind trial:here the participant is not aware whether he belongs to study group or control group. Double blind trial;Here neither the doctor nor the participant is aware of the group allocation and the treatment received.Triple blind trial:Here the participant,the investigator and the analyzer are all ‘’blind’’.

First important code of ethics was the NURENBURG CODE of 1947. “No research could proceed in human subjects without voluntary consent.”Declaration of Helsinki code of ethics on principles of ethical behaviour was established in HELSINKI-I in 1975.The term “clinical research” to “biomedical research” was revised in HELSINKI- II in 1975

institutional ethics committee or institutional review boardInstitutions undertaking clinical trials have to constitute an Institutional Ethics Committee (IEC) or Institutional Review Board (IRB). It is mandatory that each dissertation research proposal (synopsis) involving humans (irrespective of type of study, including questionnaire based surveys) or animals should be accompanied by a clearance letter from IEC.

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