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Research methodology /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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  • 1. Good MorningGood Morning INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  • 2. RESEARCH METHODOLOGY Dr. Murtuza M. Agashiwalawww.indiandentalacademy.com
  • 3. Contents • Introduction • Research - defn. and types, scientific foundation • Hypothesis – formulation, types • Steps in conducting research • Sampling techniques • Data - types and measuring • Study designs – descriptive, analytical, experimental • Ethical issues • Matching and Bias – types, prevention • Evidence based hierarchy • Metanalysis • Conclusion • References www.indiandentalacademy.com
  • 4. Introduction Why do Research? - To promote basic knowledge. - To develop new treatment modalities. - To inform the public - For effective planning of available resources. - For commercial success. - For intellectual dependence. - As a partial fulfillment to obtain Master’s Degree www.indiandentalacademy.com
  • 5. • Research is a quest for knowledge through diligent search or investigation or experimentation aimed at the discovery and interpretation of new knowledge. -Health research methodology, WHO. • Research is a careful investigation or inquiry specially through search for new facts in any branch of knowledge. -Advanced learners dictionary. • Research is a systematized effort to gain new knowledge - Redman and Mory DEFINITION OF RESEARCH www.indiandentalacademy.com
  • 6. RESEARCH METHODOLOGY 1. Is a way to systematically solve the research problem 2. It may be understood as a science of studying how research is done systematically 3. It not only involves research methods but also extends to consider the logic behind the methods www.indiandentalacademy.com
  • 7. TYPES OF RESEARCH All research can be broadly classified into two types: 1. BASIC Vs APPLIED 2. OBSERVATIONAL Vs EXPERIMENTAL 3. QUALITATIVE Vs QUANTITATIVE 4. CONCEPTUAL Vs EMPIRICAL www.indiandentalacademy.com
  • 8. BASIC Vs APPLIED • Basic research is also called fundamental research. It is a search for knowledge without a defined goal of utility or purpose. • Applied research is problem oriented and it is directed toward a defined and purposeful end. It is done based on a perceived need and helps in solving an existing problem. www.indiandentalacademy.com
  • 9. OBSERVATIONAL Vs EXPERIMENTAL RESEARCH • There are fundamentally two ways in which research questions can be answered:- • We can observe what naturally happens in the real world without interfering with it. ( OBSERVATIONAL) OR • We can manipulate some aspect of the environment and observe its effects ( EXPERIMENTAL) www.indiandentalacademy.com
  • 10. • Qualitative research deals with subjective aspects which are qualitative or qualities by nature which are difficult to quantify. Eg: Motivation research. • Quantitative research is based on the measurement of quantity or amount. It deals with objective aspects. Eg: Material science research QUALITATIVE Vs QUANTITATIVE www.indiandentalacademy.com
  • 11. CONCEPTUAL VS EMPIRICAL CONCEPTUAL Research is that related to some abstract idea or theory. It is generally used by philosophers and thinkers to develop new concepts or Re-interpret the existing ones EMPIRICAL Research is that in which experience or observation alone are the tools of research. It is data-based research and it can be further verified by observation or experimentation. www.indiandentalacademy.com
  • 12. SCIENTIFIC FOUNDATIONS OF RESEARCH 1) Order 2) Inference & chance 3) Maintenance of probability 4) Hypotheses www.indiandentalacademy.com
  • 13. ORDER Research employs an organized observation of entities or events which are classified or ordered on the basis of common properties & behaviors. The commonality among the observations help in predictions which carry to the ultimate become laws. www.indiandentalacademy.com
  • 14. INFERENCE & CHANCE Reasoning or inference is the force of advance in research. There are two distinct approaches in the development of inferences DEDUCTIVE – It moves from the general to the specific. Hence it does not allow for the element of chance. It is not used much in health research. INDUCTIVE – It moves from specific to the general. There is extrapolation of results from a sample to the target population. Health research depends almost entirely upon inductive reasoning. Hence chance must be fully accounted for. www.indiandentalacademy.com
  • 15. MAINTENANCE OF PROBABILITY Maintaining a very high probability & eliminating the chance occurrence is critical to ensure the validity of a research. Techniques used to maintain high probability are- 1. Representative sampling 2. Randomization in selection of study groups 3. Maintenance of comparison groups as controls 4. Blinding procedures 5. Statistical methods www.indiandentalacademy.com
  • 16. Hypothesis is defined as a presumption, supposition or assumption derived either out of observation or reflection. Hypothesis are carefully constructed statements generated from inferences & they use argument of induction. HYPOTHESIS www.indiandentalacademy.com
  • 17. METHODS OF GENERATING HYPOTHESIS Mill’s canons of inductive reasoning are frequently utilized in the forming of hypothesis. It involves following methods- 1. The method of difference 2. The method of agreement 3. The method of concomitant variation 4. The method of analogy www.indiandentalacademy.com
  • 18. MILL’S CANONS OF INDUCTIVE REASONING 1.Method of difference: When the frequency of a disease is markedly dissimilar under two circumstances and if a factor can be identified in one circumstance and not in the other, then this factor either its presence or absence may be the cause of the disease. e.g.: Lung cancer and Smoking Fluoride in water and Caries. www.indiandentalacademy.com
  • 19. 2. Method of agreement: If a factor’s presence or absence is common to number of circumstances that are found to be associated with the disease then that factor may be causally associated with disease. E.g.: Hepatitis A associated with patient contact, crowding, poor sanitation etc. www.indiandentalacademy.com
  • 20. 3. Method of concomitant variation; ( Dose Response effect) Eg. Decreasing level of Iodine, with increasing expression of Goiter. Increasing level of Radiation resulting in increase in number of Leukemia cases. www.indiandentalacademy.com
  • 21. 4. Method of analogy The distribution and frequency of a disease or effect may be similar enough to that of some other disease to suggest commonality in cause. Eg. Hepatitis B virus infection and cancer of the liver. www.indiandentalacademy.com
  • 22. Formulation of hypothesis • Should specify : – The population – Specific cause – Expected outcome – Dose response relationship – Time response relationship www.indiandentalacademy.com
  • 23. EXAMPLE OF HYPOTHESIS • E.g. ‘cigarette smoking causes lung cancer’ – incomplete • ‘the smoking of 30-40 cig/day causes lung cancer in 10% of smokers after 20 yrs of exposure’ www.indiandentalacademy.com
  • 24. I.  Directional hypothesis  Non directional hypothesis II.  Research hypothesis  Null hypothesis III.  Simple hypothesis  Complex hypothesis TYPES OF HYPOTHESIS www.indiandentalacademy.com
  • 25. 1.Directional hypothesis Is one that specifies not only the existence but the expected direction of the relationship between variables. E.G - Higher the anterior overjet higher the chances of anterior teeth fracture. www.indiandentalacademy.com
  • 26. 2.Non directional hypothesis Does not stipulate the direction of the relationship. A. There is an association between the degree of anterior overjet and anterior teeth fractures. www.indiandentalacademy.com
  • 27. 1.Research hypothesis (substantive or scientific hypotheses): Are statements of actual expected relationships between variables. Those which indicate researchers true expectations. Eg; Higher the daily intake of refined sugars higher the DMFT score in children 2.Null hypothesis ( statistical hypothesis) state that there is no relationship between the independent variables and dependent variables. Eg; there is no relationship between daily intake of refined sugars and DMFT score in children www.indiandentalacademy.com
  • 28. 1.Simple hypothesis: A hypothesis can predict the relationship between a single independent variable and a single dependent variable. 2.Complex hypothesis: It can predict a relationship between two or more independent variables or two or more dependent variables. www.indiandentalacademy.com
  • 29. E) DATA COLLECTION by 1.Mere Observation 2.Intervention followed by observation PROCEDURAL STEPS IN CONDUCTING RESEARCHPROCEDURAL STEPS IN CONDUCTING RESEARCH A) CONCEPTUALIZING THE PROBLEM Need Background Rationale B) FORMULATING THE OBJECTIVES Generating hypotheses Testing hypotheses C) DESIGNING THE APPROACH Research design Methods and materials D) DEFINING THE POPULATION Target population Study population F) ANALYSIS & INTERPRETATION OF RESULTS G) REPORTING OR PUBLICATION OF THE STUDYwww.indiandentalacademy.com
  • 30. Sampling • Sampling is the process or technique of selecting a sample of appropriate characteristics and adequate size. • The individuals, records, units or time are considered to be elements in the sample. • An element is the unit of observation or unit about which information is collected and which is the subject of analysis. www.indiandentalacademy.com
  • 31. Sampling • The total of the elements of the population under the survey is called “sampling frame”. • The sample is drawn from this survey population and is subset of the sampling frame. • The sampling frame may be used in toto for sampling (simple random sampling) or may be divided into sub-groups or strata decided by age, sex, class (stratified sampling); or the frame may consist of areas or clusters of big units containing smaller units ( cluster & multistage sampling). www.indiandentalacademy.com
  • 32. Advantages of Sampling: 1) Sampling reduces the cost of investigation, the time required and the number of personnel involved. 2) Sampling is especially important when the tests used are highly technical or detailed or must be administered or interpreted by experts. 3) Sampling allows thorough investigation of the units of observation. 4) It is obvious that a sample can be covered more adequately and in more depth in a research project than can a total population. Therefore, Sampling is a more cost efficient way of collecting data. www.indiandentalacademy.com
  • 33. Requisites for a Reliable Sample 1) Efficiency - Ability of the sample to yield the desired information. 2) Representativeness - inferences drawn from the sample can be generalized to that population with measurable precision and confidence. 3) Measurability - The design of the sample should be such that valid estimates of its variability can be made. In other words, the investigator should be able to estimate the extent to which the findings from the sample are likely to differ from what we would have found had we studied the entire parent population. 4) Size - A sample should be large enough to minimize sample variability to allow estimates of the population characteristics to be made with measurable precision. www.indiandentalacademy.com
  • 34. 5) Coverage - Adequate coverage of the sample is essential if it is to remain representative. High rates of refusal, unavailability, loss of follow up and other missing data can render a sample unrepresentative of the parent population. 6) Goal Orientation - Sample selection and estimation procedures should be oriented towards the study objectives and research design and considerations. 7) Feasibility - The design should be simple enough to be carried out in practice. 8) Economy and Cost Efficiency - The sample should therefore yield the desired information within expected but tolerable limits of sampling error for the lowest cost. Requisites for a Reliable Sample www.indiandentalacademy.com
  • 35. Sampling Procedure Probability samples Non-Probability samples www.indiandentalacademy.com
  • 36. Probability samples Probability samples are those in which it is possible to ascertain the probability that a unit of the population is included in the sample. The common types of probability samples are :- i) Simple Random Sampling - It guarantees that each member of the population has an equal chance of being included in the sample. •The two common methods of random sampling are lottery and tables of random numbers. • The lottery method assigns numbers to the population; these numbers are then thoroughly mixed and a sufficient number drawn (without replacement) to provide the desired sample size. •Tables of random numbers are used after numbers (eg- sequential counts) have been assigned to members of the study population. www.indiandentalacademy.com
  • 37. ii) Systematic Sampling- The first unit is chosen at random and then other units for the sample are chosen in a systematic way. eg:- every other person or every fifth person. iii) Stratified Random Sampling- It is obtained by using the following procedure:- The population to be sampled is divided into groups known as strata, such that each group is homogeneous in its characteristic. A simple random sample is then drawn from each stratum. This type of sampling is used when the population is heterogeneous with regard to the characteristic under study. Eg:- population divide into different age groups and then samples are selected from the groups randomly. This method ensures more representativeness, provides greater accuracy and can concentrate on wider geographical area. Care must be taken while dividing the population into strata.www.indiandentalacademy.com
  • 38. iv) Cluster Sampling- It involves choosing groups of units or clusters at random. All the units in each group, or samples of them are then used in the study. Eg:- villages, wards, school children. This method is simpler and involves less time and cost, but gives a higher standard error. v) Multistage Sampling- The first step is to select the groups or clusters. Then the sub samples are then taken in as many subsequent stages as necessary to obtain the desired sample size. E.g.:- choice of states within countries --- 4 Choice of districts within states --- 4 and so on. www.indiandentalacademy.com
  • 39. vi) Multiphase Sampling- It is used to take basic data from a large sample and details from sub sample. This is different from multistage sampling, in which the same amount of information is obtained for every unit. www.indiandentalacademy.com
  • 40. Non probability sampling i) Accidental or incidental sampling – people who have assembled in a common place with a common interest or accidentally are surveyed eg. Diabetes in football match ii) Sequential Sampling- Here a small sample is tested in order to answer certain questions about the population. If the questions are not answered, the number of subjects or units in the sample is increased gradually until conclusions may be drawn. www.indiandentalacademy.com
  • 41. iii) judgment sampling – Sample selection is based on the judgment of the person entrusted with the job iv) Convenience sampling – Selection is made from available source like telephone directory, automobile registers, cards, stock exchange directory etc. www.indiandentalacademy.com
  • 42. • Discrete:- They are called as attributes. They are qualitative in nature e.g.: Race, Sex, Religion etc. • Continuous:- They are also called variables. They are quantitative in nature. e.g.: Height, weight, RBC’ count etc. TYPES OF DATA www.indiandentalacademy.com
  • 43. Four principal scales : 1.Nominal scale 2.Ordinal scale 3.Interval scale 4.Ratio scale SCALES OF MEASUREMENT OF DATA www.indiandentalacademy.com
  • 44. 1. Nominal scale:- This scale uses names or tags to distinguish one measurement from another. It does not imply magnitude of individual measurements. Eg. Classification of sex, Classification of religion. www.indiandentalacademy.com
  • 45. Ordinal scale:- it is like nominal scale but there exists an implicit graded order relationship among the categories. Eg. Pain measured as: Mild – 1 Moderate – 2 Severe – 3 or Socio economic status measured as Class I Class II Class III Class IV Stages of cancer as I, II, IIIa, IIIb & IVwww.indiandentalacademy.com
  • 46. • Interval scale: A numerical unit of measurement is used in this scale. The difference between any two measurements can be clearly identified in terms of an interval between two points of scale. This scale has no true zero point Eg. Measurement of body temperature in degrees of Celsius. www.indiandentalacademy.com
  • 47. Ratio scale • It is as same as interval scale in every aspect except that measurement begins at a true or absolute zero. eg. Weight in Kgs, Height in Mts. There cannot be negative measurements. www.indiandentalacademy.com
  • 48. EPIDEMIOLOGY EPI = AMONG DEMOS = PEOPLE LOGOS = STUDY DEFINITION OF EPIDEMIOLOGY "Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations and the application of this study to the control of health problems." (Last, 1988) -WORLD HEALTH ORGANIZATION www.indiandentalacademy.com
  • 49. Classification of studies •Descriptive study •Analytical study Cross sectional studyCross sectional study Case control studyCase control study Cohort- follow upCohort- follow up Observational study Experimental study •Randomised control trials/ clinical trials • field trial/ community intervention trial •Community trial All these study complement each other www.indiandentalacademy.com
  • 50. www.indiandentalacademy.com
  • 51. Design Options • Directionality • Timing www.indiandentalacademy.com
  • 52. Directionality • When the exposure variable is observed relative in time to when the health outcome is observed. www.indiandentalacademy.com
  • 53. Forward Directionality www.indiandentalacademy.com
  • 54. Backwards Directionality www.indiandentalacademy.com
  • 55. Non-Directionality www.indiandentalacademy.com
  • 56. Timing • Timing concerns whether the health outcome of interest, and therefore all study events, has already occurred before the study actually began. www.indiandentalacademy.com
  • 57. Retrospective www.indiandentalacademy.com
  • 58. Prospective www.indiandentalacademy.com
  • 59. DESCRIPTIVE STUDYDESCRIPTIVE STUDY www.indiandentalacademy.com
  • 60. Descriptive study • Allows…formulation of hypothesis… • 1st phase of an investigation They ask the question – When…time dist – Where…place dist – Who… person dist www.indiandentalacademy.com
  • 61. • Procedure in descriptive study – Defining population to be studied – Defining disease under study – Describing distribution by time, person n place – Measurement of disease – Comparing with known indices – Formulation of etiological hypothesis Descriptive study www.indiandentalacademy.com
  • 62. • Def the population – Age , sex, occupation, culture, characteristics n similar information – Population should be large enough – Stable of migration – No visitors n relative Provide denominator for calculating rates, measurement of frequency, distribution n determination of disease Descriptive study www.indiandentalacademy.com
  • 63. • Def the disease under study – Precise and valid – Operational defined…. Identified n measured • Describing the disease – Distribution…time, place , person – Time trends or fluctuations • Short term fluctuation • Periodic fluctuation • Long term fluctuation Descriptive study www.indiandentalacademy.com
  • 64. – Place distribution – b/w countries • Genetic Vs environment • Role of diet • Migration changes • Geographic variations – Person distribution – natural history of disease. Descriptive study www.indiandentalacademy.com
  • 65. • Measurement of disease : – Mortality- – Morbidity- • incidence – longitudinal stud. • prevalence - cross sectional stud. – Disability • Comparing with known indices Descriptive study www.indiandentalacademy.com
  • 66. • Formulation of hypothesis • Should specify : – The population – Specific cause – Expected outcome – Dose response relationship – Time response relationship • E.g. ‘cigarette smoking causes lung cancer’ – incomplete • ‘the smoking of 30-40 cig/day causes lung cancer in 10% of smokers after 20 yrs of exposure’ Descriptive study www.indiandentalacademy.com
  • 67. • Uses : – Data regarding magnitude of disease load and types of disease problem – Clues – disease Etiology and helps in formulation of hypothesis – Background data – P, O & E curative services – Describe variation in disease occurrence by time, place and person Descriptive study www.indiandentalacademy.com
  • 68. ANALYTICAL STUDYANALYTICAL STUDY www.indiandentalacademy.com
  • 69. Analytical studies • Second major type of study after descriptive study. • Interest – individual…instead of population • Test a hypothesis – Determine Statistical association – Strength of association • 2 types : – Case control study – Cohort study www.indiandentalacademy.com
  • 70. CASE-CONTROL STUDIES www.indiandentalacademy.com
  • 71. Case-Control Study • Directionality: Always backwards • Timing: Always Retrospective ? www.indiandentalacademy.com
  • 72. Case-control study design Exposure Disease Observer ? Choose groups with and without disease, look back at what different exposures they may have had www.indiandentalacademy.com
  • 73. Case control studies • Attempt to make inference from existing observations (retrospective) • Compares patients with outcome/disease with those without and attempts to identify factors that influenced that outcome (or caused that disease) • Important concept: start with the result (disease) and work backwards for the cause www.indiandentalacademy.com
  • 74. • Basic steps : – Selection of cases & controls – Matching – Measurement of exposure – Analysis & interpretation www.indiandentalacademy.com
  • 75. Strengths of case-control design • Best study when have rare disease or outcome • Relatively quick and inexpensive www.indiandentalacademy.com
  • 76. Weaknesses (potential biases) • Selection (confounding) bias : controls must be as similar to cases as possible without any confounding factors • Berkinsonian bias…rates of adm. to hospital • Recall bias : cases may be able to remember events better because of its significance or may be prompted to remember by investigators • Survival bias: dead people don’t make it into many case-control studies; and if they are alive, they don’t remember things very well • Interviewer’s bias www.indiandentalacademy.com
  • 77. Ways to combat weakness • Matching: for each case, find a control that looks just like him/her in all other possible ways except for the disease (same age, race, economic class, etc.) • Blinding: individual assessing exposures should be blinded to whether the person is a case or control www.indiandentalacademy.com
  • 78. Types of blinding • Single blind trial – participant is not aware whether he belongs to case or control group. • Double blind trail – neither doctor nor participant • Triple blind trial – participant, doctor and the person analyzing data www.indiandentalacademy.com
  • 79. Cohort Studies/Prospective study/ Longitudinal/ Incidence/Forward-looking study www.indiandentalacademy.com
  • 80. Cohort studies • Studies whether exposure to a “risk factor” is associated with a subsequent “outcome” • Select two populations who seem the same except for the hypothesized risk factor • Follow them and see how many have the outcome or disease • Important concept: Start with the risk, then look for the outcome www.indiandentalacademy.com
  • 81. • Consideration in assembling cohorts – Free of disease – Equally susceptible to disease – Comparable groups – Diagnostic n eligibility criteria must be defined before hand www.indiandentalacademy.com
  • 82. Cohort Study • Directionality: Always forward Exposure Study Begins Study Begins www.indiandentalacademy.com
  • 83. Prospective Cohort study design Exposure Observer Disease ? Start with two groups of people who are exposed and unexposed, follow them to see who gets disease. www.indiandentalacademy.com
  • 84. Cohort Study Design (Retrospective/Historical) Exposure Disease Observer ? Start with two groups of people who are exposed and unexposed, find out who got the disease. www.indiandentalacademy.com
  • 85. Prospective vs. Retrospective Cohort • Prospective: start with exposed and unexposed groups, wait for the outcome • Retrospective: both exposure and outcome have already happened, but groups are still made based on exposed or unexposed www.indiandentalacademy.com
  • 86. Strengths of cohort study • Not only can you look at risk, you can calculate how many people actually get the disease (incidence rates) • Since you enroll subjects before the outcome, you can measure multiple exposures without recall bias • Best for rare exposures www.indiandentalacademy.com
  • 87. Some problems with cohorts • Time consuming • Large sample size required • Expensive • Attrition of study group www.indiandentalacademy.com
  • 88. 1.Selection of study subjects • General population • Select group…. Special exposure…. Degree or duration of exposure 2.Obtaining data on exposure • Cohort members • Review of records • Medical examination/special tests • Environmental surveys Steps of Cohort study www.indiandentalacademy.com
  • 89. 3.Selection of comparisons group • Internal comparisons… basis of degree / levels of exposure • External comparison with general population • Periodic medical examination • Reviewing physician n hospital records • Surveillance of death record • Mailed questionnaires, tele calls 4.Follow - up www.indiandentalacademy.com
  • 90. 5.Analysis • Incidence rates of outcome among exposed n unexposed • Estimate of risk • Risk estimate done in terms of- – Relative risk … strength of association b/w risk factor n disease – Attributable risk • In diff in incidence rates of disease b/w exposed grp n non exposed • Extent the disease under study can be attributed to exposure www.indiandentalacademy.com
  • 91. Relative risk Vs. Attributable risk • RR is imp in etiological enquires • Increase in RR … inc cause n effect association • AR .. Impact of successful preventive or public health programme on the problem www.indiandentalacademy.com
  • 92. Cross-Sectional Study • Directionality: Always Non-directional • Timing: Always Retrospective www.indiandentalacademy.com
  • 93. Cross-Sectional Study Advantages: • Convenient and inexpensive • Can consider several exposures and several diseases • Can generate hypotheses • Usually represents the general population www.indiandentalacademy.com
  • 94. Cross-Sectional Study Disadvantages: • Cannot establish whether the exposure preceded disease or disease influenced exposure • Can identify only prevalent cases rather than incident cases • Possible bias since only survivors are available for study • May under-represent diseases with short duration www.indiandentalacademy.com
  • 95. EXPERIMENTAL STUDYEXPERIMENTAL STUDY www.indiandentalacademy.com
  • 96. Experimental studies • Final / definitive step • Direct intervention Only Results from Experimental Studies Can Demonstrate Cause and Effect Relationships www.indiandentalacademy.com
  • 97. The investigator through randomization allocates subjects to different categories of exposure. BASIC IDEA www.indiandentalacademy.com
  • 98. www.indiandentalacademy.com
  • 99. 1. To promote “Scientific Proof” of aetiological factors. 2. To provide a method of measuring the effectiveness and efficiency of health services. Aims of experimental studies www.indiandentalacademy.com
  • 100. 1. ANIMAL EXPERIMENTS 2. HUMAN EXPERIMENTS CLASSIFICATION OF EXPERIMENTS www.indiandentalacademy.com
  • 101. Animal studies are done for the following purposes a) Experimental reproduction of human disease in animals to confirm aetiological hypothesis. b) To test the efficacy of various therapeutic and preventive measures such as vaccines and drugs. c) To study the natural history of disease. Animal experiments are done on carefully bred animals in controlled environments. PURPOSES OF ANIMAL STUDIES www.indiandentalacademy.com
  • 102. 1. Animals are bred in laboratories and manipulated easily according to wishes of the experimenter. 2. They multiply rapidly and enable experimenter to carry out certain experiments which are not possible in human beings. ADVANTAGES www.indiandentalacademy.com
  • 103. 1. All human diseases cannot be reproduced in animals. 2. Results of animal studies cannot be extrapolated to human beings. LIMITATIONS www.indiandentalacademy.com
  • 104. 1. They are done on humans and very much needed to investigate disease etiology. 2. They are also done to evaluate the preventive and therapeutic measures. eg. James Lind (1747) – Study done on Sailors to reveal the association of lemons, oranges in diet on scurvy among a group of Sailors. Edward Jenners (1796) experimental work with Cowpox to develop vaccine against Small pox. 3.Human studies should be carefully designed because they involve logistic and ethical implications HUMAN EXPERIMENTS www.indiandentalacademy.com
  • 105. They are broadly divided into two types 1. Randomized Controlled Trials 2. Non Randomized Trials CLASSIFICATION OF EXPERIMENTAL STUDIES www.indiandentalacademy.com
  • 106. RCT is considered as the gold standard in epidemiology and perhaps the most concrete evidence for establishing association. RANDOMIZED CONTROLLED TRIALS www.indiandentalacademy.com
  • 107. Types Of Randomized Controlled Trial CLINICAL TRIAL - concerned with evaluating therapeutic agents like drugs. PREVENTIVE TRIALS - purported to prevent or eliminate diseases on an experimental basis. RISK FACTOR TRIALS - A trial of risk factors in which the investigator intervenes to interrupt the usual sequence in the development of disease. www.indiandentalacademy.com
  • 108. 1. Drawing up a protocol 2. Selecting reference and experimental Populations 3. Randomization 4. Manipulation or Intervention 5. Follow-up 6. Assessment of outcome STEPS IN RCT DESIGN www.indiandentalacademy.com
  • 109. Select suitable population (Reference or Target Population) Select suitable sample (Experimental or study population) Those not eligible Those who do not wish to give consent Make necessary exclusions RANDOMIZE Experimental group Control Group Manipulation & Follow up Assessment DESIGN OF A RANDOMIZED CONTROLLED TRIAL www.indiandentalacademy.com
  • 110. 1. Concurrent Parallel Study 2. Cross-over type of Study STUDY DESIGNS IN RCT’S www.indiandentalacademy.com
  • 111. Patients Random Assignment Exposed to specific Treatment Unexposed to specific treatment Observation Compare Outcome Compare Outcome Exposed and Unexposed to treatment CONCURRENT PARALLEL STUDY DESIGN CROSS-OVER TYPE OF STUDY DESIGN Time Patients Random Assignment Exposed to specific Treatment Unexposed to specific treatment Observation Time www.indiandentalacademy.com
  • 112. 1. Researcher has ‘control’ over the intervention (s). 2. Results are ensured. 3. Reliable and well-respected research design 4. Individual factors can be identified. ADVANTAGES OF EXPERIMENTAL RESEARCH DESIGNS www.indiandentalacademy.com
  • 113. 1. Problems in dealing with multiple causation; isolating individual factors may over-simplify complex issues. 2. Ethical issues. 3. Researcher bias and subjectivity in research design, methods and analysis. 4. Hawthorne effect upon groups being researched . DISADVANTAGES OF EXPERIMENTAL RESEARCH DESIGNS www.indiandentalacademy.com
  • 114. Ethical aspect • All innovative scientific interventions, whether diagnostic, prophylactic, or therapeutic should ultimately be evaluated in human subjects • The need for safeguards in human experimentation cannot be overemphasized and several important codes have been developed for protection of human subjects • Three underlying principles are 1. Beneficence, which requires that good should result, harm should be avoided or that benefits should justify the expected risk or harm 2. Respect for rights, including free choice of the subject and protection for those of diminished autonomy 3. Justice, which requires a equal distribution of burden and benefits www.indiandentalacademy.com
  • 115. International Declarations: • The first code was “ the Nuremberg Code of 1947” • This was followed by the “Declaration of Helsinki” which was adopted by The World Medical Association and the W.H.O in 1975. www.indiandentalacademy.com
  • 116. HELSINKI GUIDELINES: a) Biomedical research should follow scientific principles and should be based on adequately performed laboratory and animal experimentation. b) The design of each procedure involving humans should be clearly formulated in an experimental protocol. c) the experiment should be conducted by scientifically qualified persons under supervision of medical experts. d) The right of the research subject to safeguard his/ her integrity must always be respected. e) The accuracy of the research results must be preserved. www.indiandentalacademy.com
  • 117. f) In any research on humans, each subject be informed about the aim, methods, benefits and potential hazards of the study. g) When obtaining informed consent for research, a doctor should be cautious if the subject is in a dependant relationship to him/ her. h) In case of legal competence, informed consent should be obtained from the legal guardian. i) Subjects should be informed that they are free to abstain or to withdraw from participation at any time. HELSINKI GUIDELINES: www.indiandentalacademy.com
  • 118. HIERARCHY OF EVIDENCE SYSTEMATIC REVIEWS & META ANALYSIS RCTs LONGITUDINAL COHORT STUDIES CASE-CONTROL STUDIES CROSS SECTIONAL STUDIES CASE REPORTSwww.indiandentalacademy.com
  • 119. Meta Analysis • New concept in research • Coined by Glass in 1976 “Metanalysis is nothing but combining the results of several clinical studies on the same subject to derive definitive conclusions.” www.indiandentalacademy.com
  • 120. • Like a review article, begins with a literature review identifying studies of similar research question. • Later it attempts to analyze statistically the aggregate results to derive a single integrated question www.indiandentalacademy.com
  • 121. Uses • It scrutinizes studies to explain why research results differ • Identify new direction for research • Useful in the research of rare diseases • Decides on the best clinical approach to the problem www.indiandentalacademy.com
  • 122. Conclusion • Thus the study of research procedures and methods is very important aspect of all post graduate students and at the same time provide guidelines on which our future research would be based. • It also shows us the procedures that need to be followed while undertaking research and also shows us, how the data or findings of our study should be presented for correct interpretation and for publication. www.indiandentalacademy.com
  • 123. References • Health research methodology : a guide for training in research methods - World Health Organization • Preventive and social medicine - K. Park • Essentials of preventive and community dentistry - Soben Peter • Methods of biostatistics - T Bhaskara Rao www.indiandentalacademy.com
  • 124. Thank You www.indiandentalacademy.com For more details please visit www.indiandentalacademy.com

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