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  • (what techniques of gathering data will be adopted) eg. Questionnaires.sample is a group of individual actually available 4 investign
  • All cases admitted or discharged from a hospital, clinic, or private practice with in a specified period.survey or disease registry
  • Manipulate by deliberate application orwithdrawl or reduction of suspected causal factor,as laid down in protocol,this manipulation creates an indivudualvariable,whose effect is determined by measurement of final outcome.
  • Transcript

    • 1. Research methodology
    • 2. contents
      Introduction to research
      Why to do a research
      Categories of research
      Research methods & research methodology
      Procedural steps in research
      Research strategy
      epidemiologic studies
      Ethics in research
    • 3. 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.
    • 4. definitions
      Research(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.
    • 5. 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
    • 6. Dissertation:
      • Dissertation means “to discuss”.
      • 7. It is an academic activity laid down by the university for the partial fulfillment of MDS degree.
      • 8. It is an exercise to train a PG student to plan, execute, evaluate, write and report a scientific project.
      • 9. It is an in-depth study of a particular topic which contributes new information and knowledge in the field
      • 10. 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.
    • 11. Categories of research
      Empirical researchandtheoretical research
      Basic researchandApplied research
      Observational research
      • Experimental research
    • Basic or pure research
      It 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.
    • 12. Applied research
      It 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
    • 13. Research methods
    • 14. methods/ techniques that are used for conducting research are termed as research methods or research techniques.
      They fall into 3 groups
      Those concerned with collection of data
      Those statistical techniques which are used for establishing relationship between the data and the unknown
      Those methods which are used to evaluate the accuracy of the results obtained.
    • 15. Research methodology
      It 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 undertaken
      How the research problem has been defined
      In what way and why the hypothesis has been formed
    • 16. What data has been collected
      What particular method has been adopted for collection of data
      Why 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
    • 17. Procedural steps in research
    • 18. Selection of problem for investigation-further exploration
      Inexperienced-seek opinion –senior
      Constructing –essential starting point
      Review literature
      Modern electronic research
      Abstract collection held on CD-ROMS-enables –key words
      Medline and psyclit database
      Role 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.
    • 19. Specifying study design
      Selection 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
      5-strongly disgree
      May not exist for the study ,this may necessiate the development of new scale.
      should possess Reliability and validity
    • 20. 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
    • 21. Ethical approval
      Pilot work
      Main study
      Analysis of results
      Report writing
    • 22. Research strategies
      Selection 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.
    • 23. Classification of Epidemiologic studies
    • 24. Decscriptive study
      Concerned with observing the distribution of disease or health related characteristics in human population
      • Eg. Surveys.
      • 25. Defining population:denominator
      • 26. Defining the disease:operational definition.
      • 27. Describing disease-time,place and person
      Short term fluctuation:
      Common source epidemics-single,continuous
      Propagated epidemics-person to person transmission of infectious agent---epidemics of hepatitis A and poliomyelitis
      Slow or modern epidemics
    • 28. Periodic fluctuations:
      Seasonal –communicable diseases like measles,varicella,malaria
      Eg:upperResp tract infections inc during winter and GI inf in summer
      Cyclic trends-measles-incidence every 2-3 yrs
      Influenza occurs at intervals of 7-10 yrs
      Long term fluctuation
      Changes occur over long period of time,change in frequency encompassing sev decades
      Eg:CHD,diabetes,lung cancer shows upward trend in 50 decades and TB, typhoid downward
      Place distribution:
      National-endemic disease like goitre,flourosis
      Rural-urban-lung cancer,cardiovascular accidents-urban
      Local-spot maps (john snow –on epidemic of cholera)and shaded maps -study
    • 29. Person distribution:age sex
      Measurement of disease :morbidity and mortality indicators
      Expressed in terms of incidence and prevalence
      Comparing with known indices:comparision b/n different population and subgroups of same populn-clue to etiology
      Formulation 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.
      magnitude and type of disease in community
      Clues to etiology
      contributes to research
    • 30. surveys
      Surveys are methods of scientific or systematic collection of data, compiling, presenting in order (useful manner), analysing and evaluating them
      The focus of attention must be on the following
      Formulating the objective of the study-obj describing what is to be measured,resources
      Designing the method of data collection eg. Questionnaires, interviewing, examination of records or observations
      Selecting the sample
    • 31. Collection of data through questionnaires
      Questionnaire 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 clear
      First 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
    • 32. Conducting examination:
      Obtaining approval from authorities
      Emergency care and refferal
      (diagnostic method)Validity and reliabilty of the data
    • 33. Classification of study types-ADA(1970)
      typeI: complete examination
      typeII: limited examination
      Type III: inspection
      Type IV:screeningprocedures:tongue depressor
      d) Analysing the data
      e)Drawing the conclusion
      f) Publishing the reports
    • 34. Case study: it is an intensive investigation of a person, a family, a group, a social institution or an entire community in a natural setting
      Correlational study: it is a descriptive research technique utilized to identify consistent relationship among variables
    • 35. Analytical study
      Second major type
      Subject of interest –individual with in population
      Object –not to formulate but test hypothesis
      Can determine:
      1.Statistical association between disease and suspected factors
      2.If exists--strength
    • 36. Case control studies
      Design of a case-control study
      Direction of enquiry
      Not Exposed
      Not Exposed
    • 37. 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
    • 38. Selection of cases
      The criteria for inclusion in the study must be clearly specified.
      Sources of cases:
      General population
    • 39. Controls
      they must be as similar to the cases as possible, except for the absence of the disease,which is under study.
      Selection of controls
      Crucial step in case-control studies
      Controls must be
      Be similar to the cases except for the absence of the disease under study
      Equal ratio
      Sources of controls
      Hospitals:diff illness
      Neighborhood controls
      General population
    • 40. Matching
      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 factor
      One which is associated both with exposure and disease; and is distributed unequally in study and control groups
      Although associated with ‘exposure’ under investigation, it itself is a risk factor for the disease
    • 41. Measurement of exposure
      Exposure can be measured by
      By studying past records
      Bias/ systematic error should be avoided while measuring the exposure
    • 42. Analysis
      Involves two steps
      Exposure rates among cases and controls
      Estimation of disease risk associated with exposure (odds ratio)
    • 43. 1. Exposure rates
      A case control study of smoking and lung cancer
      Exposure rate among cases= (a/a+c)100 = (33/35) 100 = 94.2 %
      Exposure rate among controls= (b/b+d)100 = (55/82) 100 = 67 %
    • 44. 2.Estimation of risk
      Incidence among exposed
      Relative risk =
      Incidence among non exposed
      Relative risk (RR) or Risk ratio
      = a/(a+b) / c/(c+d)
    • 45. Odds ratio (cross product ratio)
      It is a key parameter in the analysis of case control studies
      A measure of the strength of the association between risk factor and outcome
      Derivation of odds ratio is based on 3 assumptions
      Disease under investigation is a rare one
      Cases are representative of those with disease
      Controls are representative of those without disease
    • 46. Odds ratio = ad/bc = 33 X27/ 55X2 = 8.1
      Smokers have a risk of having lung cancer 8.1 times that of non smokers
    • 47. Bias in case control study
      Bias due to confounding
      Memory bias
      Selection bias
      Berksoniansbias:different rates of admission to hosp for people with diff disease
      Interviewer’s bias
    • 48. advantages of …
      Relatively easy to carry out
      Rapid and inexpensive (compared with cohort studies)
      Require comparatively few subjects
      suitable to investigate rare diseases or diseasesabout which little is known.
      No risk to subjects
      Allows 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 future
      Ethical problems minimal
    • 49. Disadvantages of …
      High chances for bias
      Validation of information obtained is difficult or sometimes impossible
      Selection of an appropriate control group may be difficult
      We cannot measure incidence, and can only estimate the odds ratio but not relative risk
      Not suited to the evaluation of therapy or prophylaxis of a disease
      Another major concern is the representativeness of cases and controls
    • 50. Cohort studies
      Usually undertaken to obtain additional evidence to refute or support the existence of an association
      between suspected cause and disease
      Other names
      Incidence study
      Forward looking study
      Longitudinal study
      Prospective study
    • 51. distinguishing Features of …
      Cohorts are identified prior to the appearance of the disease under investigation
      Study groups are observed over a period of time to determine the frequency of disease
      The study proceeds from cause to effect
    • 52. 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
    • 53. Indications for …
      When there is a good evidence of an association between exposure and disease
      When the exposure is rare but the incidence of disease is high among exposed
      When the attrition can be minimised
      When ample funds are available
    • 54. Design of a cohort study
      Direction of enquiry
      Screening to exclude those with the condition
      With the
      Do not develop
      free of condition
      Without the
      Do not develop
    • 55. Considerations for selecting cohorts
      Cohorts must be free from the disease under study
      both the groups should be equally susceptible to disease under study
      Both the groups should be comparable in respect of all possible variables, except the assumed risk factors
      Diagnostic and eligibility criteria of the disease must be defined beforehand.
      Inclusion and exclusion criteria should be clearly stated before the commencement
    • 56. Steps in …
      Selection of study subjects
      Obtaining data on exposure
      Selection of comparison groups
      Follow up
    • 57. Selection of study subjects
      Cohorts can be selected from
      General population
      Special groups
      Select groups (eg. Doctors, lawyers, teachers, etc.)
      Exposure groups
    • 58. Obtaining data on exposure
      Information can be obtained from
      Review of records
      Medical examination or special tests
      Environmental surveys
      Information about exposure should facilitate classification of cohort members
      According to whether or not they were exposed
      According to the degree of exposure
    • 59. Selection of comparison groups
      Internal comparisons: no outside comparision group is required
      External 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
    • 60. Follow up
      Periodic medical examination of each member
      Reviewing physician and hospital records
      Routine surveillence of morbidity and mortality records
      Mailed questionnaires, telephone interviews, periodic home visits
    • 61. Analysis
      Data is analysedinterms of
      Incidence rates of outcome among exposed and non-exposed
      Estimation of risk
      Relative risk
      Attributable risk
    • 62. Incidence rates
      Incidence can be measured directly
      Incidence rate among smokers = 70/7000 = 10 per thousand
      Incidence rate among non-smokers= 3/3000 = 1 per 1000
      P < 0.001
    • 63. Relative risk
      Relative risThe ratio of incidence
      among exposed and
      incidence among
      Also called ‘risk ratio’
      RR is the direct measure of strength of association between suspected cause and effect
      Incidence among exposed
      Incidence among non-exposed
      10/1 = 10
      RR-i= no assossiation
      RR > 1= positive assossiation
    • 64. Attributable risk
      Incident rate among exposed – incidence rate among non-exposed
      X 100
      Incident rate among exposed
      The difference in incidence rates between exposed and non-exposed groups
      Also called risk difference
      of lung cancer was due to their smoking
      It indicates to what extent disease can be attributed to the exposure
      Suggests the amount of disease that might be eliminated if the factor could be controlled
      (10-1/10) X 100 = 90%
    • 65. Relative risk X Attributable risk
      Relative risk
      Etiological enquiries
      Larger the RR, stronger the association between risk factor and outcome
      Does not reflect the potential public health importance
      Attributable risk
      Gives a better idea of the impact of a successful intervention might have in reducing the problem
    • 66. Advantages of cohort studies
      Allow the possibility of measuring directlythe relative risk of developing the condition for thosewho have the characteristic, compared to those who do not
      Allows for a conclusion of cause-effect relationship
      Because the presence or absence of the risk factor isrecorded before the disease occurs, there is no chanceof bias
    • 67. 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.
    • 68. Disadvantages of cohort studies
      Not 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.
    • 69. 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.
    • 70. Case control study cohort study
      Proceeds from effect to cause
      Starts with the disease
      Tests whether the suspectedexposure occurs more frequentlyin those with the disease thanamong those without thedisease.
      Involves fewer number ofsubjects
      Yields relatively quick results
      Suitable for the study of rarediseases
      Generally yields only estimateof RR (odds ratio)
      Cannot yield information aboutdiseases other than thatselected for study
      Relatively 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 subjects
      Long 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.
    • 71. Experimental studies
      Study of epidemics among colonies of experimental animals such as rats and mice .
      To provide scientific proofs of etiological factors
      To 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 feasibility
      Animal studies: important application
      Bred in lab,and can manipulated easily
      They multiply rapidly
      Not all human diseases can be reprodeuced
      All conclusions – not applicable
    • 72. Human studies:
      To investigate disease etiology and to evaluate the preventive ,therapeutic measures
      1747-john lind-scurvy
      1796-Edward Jennar-cowpox
      Ethical and logistic considerations,benefits weighed againsts the risks involved
      Volunteers –made fully aware of the experiment
      WHO (1980)-strict code of practice
    • 73. Experimental studies
      Randomised controlled trials
      Non-randomized trials
      Randomised controlled trials:
      Involves some action,intervention or manipulation such as deliberate application or withdrawl of suspected cause.
      Drawing up a protocal
      Selecting reference and experimental population
      Manipulation or intervention
      Follow- up
      Assessment of outcome
    • 74. Select population (Reference or target population)Select suitable sample (Experimental or study population)
      Selection by defined criteria
      Potential participants
      (Meet selection criteria)
      (do not meet selection criteria)
      (do not give consent)
      Invitation to participate
      Randomization &
      double blinding
      Experimental group
      Follow up
      Control group
    • 75. 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 death
      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 in
      Single 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’’.
    • 76. Ethics in research
    • 77. 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
    • 78. institutional ethics committee or institutional review board
      Institutions 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.
    • 79. ethics and its principles
      The science of ideal human character and behavior in situations where distinction must be made between right and wrong, duty must be followed and good inter-personal relations maintained.
      When considering the ethical aspect of health research the following principles should also be kept in mind. (Helsinki declaration)
    • 80. Ethical principles
      Veracity or truthfulness
    • 81. An application should be submitted to the ethics committee in the following manner
      Clear research objectives and rationale for undertaking the investigation in human subjects in the light of existing knowledge.
      Subject recruitment procedures.
      Inclusion and exclusion criteria for entry of subjects in the study.
      Precise description of methodology of the proposed research, including intended dosage of drugs, planned duration of treatment and details of invasive procedures if any.
    • 82. A description of plans to withdraw or withhold standard therapies in the course of research.
      The plans for statistical analysis of the study.
      Procedure for seeking and obtaining informed consent with sample of patient information sheet and informed consent forms in English and regional languages.
      Safety of proposed intervention and any drug or vaccine to be tested, including results of relevant laboratory and animal research.
    • 83. For research carrying more than minimal risk, an account of plans to provide medical therapy for such risk or injury or toxicity due to over dosage should be included.
      Proposed compensation and reimbursement of incidental expenses.
      Storage and maintenance of all data collected during the trial.
      Plans for publication of results- positive or negative- while maintaining the privacy and confidentiality of the study participants.
      A statement on probable ethical issues and steps taken to tackle the same.
    • 84. Considerations to be kept in mind while conducting research:
      • In any research on human beings, each subject must be adequately informed of the aim, methods, anticipated benefits and potential hazards of the study and the discomfort it may entail.
      • 85. When obtaining informed consent, we should be cautious if the subject has a dependent relationship to us. No pressure or threat should be exercised.
      • 86. In case of legal incompetence informed consent should be obtained from the legal guardian in accordance with the existing legislation.
      • 87. Subject should be informed that they are free to abstain or to withdraw from participation at any time
    • references
      • Behavioural sciences for dentistry. G.Humphris & M.S.Ling. Churchill Livingstone.2000.
      • 88. Health research methodology- a guide for training in research methods. WHO 1992
      • 89. Critical thinking; understanding and evaluating dental research. D.M.Brunette. Quintessence publishing. 1996.
      • 90. Dentistry, dental practice and community. 5th edition. B.A. Burt & S.A.Eklund. WB Saunders company.
      • 91. Park’s text book of preventive and social medicine. 19th edition. K.Park. Bhanot publishers. 2007.
    • THANK