research question and designs


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research question and designs

  1. 1. LN YaddanapudiDept. of Anaesthesia and Intensive Care, PGIMER, Chandigarh
  2. 2. How to conduct a clinicaltrial Research question Study designs CONSORT step-by-step Sample size and power calculations Randomization and blinding Data processing Simple-minded guide to hypothesis testing
  3. 3. Research Process Research question Background of the research Study design Study population Study variables Data Collection Quality control Statistical analysis Dissemination of data
  4. 4. Good research depends on a clear question understanding the context of the question being able to use appropriate methods to answer the question knowing when to stop
  5. 5. Starting points Discussion with a supervisor or colleagues, email, discussion groups, mailing lists Databases - Cochrane, NEXUS, Project Impact. "further research needed" sections of journal articles, papers, theses and dissertations in the subject area of your interest Topic definitions in encyclopaedias and "state-of-the-discipline" reviews in the journal literature
  6. 6. What are you looking for? topics where there is doubt and uncertainty disputed or contradicted statements topics where evidence is incomplete, lacking, dated topics where evidence from a study on one community or group could be compared with evidence from an associated group topics which interest you
  7. 7. Requirements Mastering the literature Being alert to new ideas and techniques  Conferences  Meet researchers  Skeptical attitude  New technologies Imagination  Observation  Teaching  Creativity  Tenacity Choosing a mentor
  8. 8. Good research question Feasible  No. of Subjects  Technical expertise  Affordable in time and money  Manageable in scope Interesting Novel  Confirms, refutes or extends previous findings  New findings Ethical Relevant  Scientific knowledge  Clinical and health policy  Future research
  9. 9. Descriptive studies Case reports Case series Population studies
  10. 10. Descriptive studies: Uses Hypothesis generating Suggesting associations
  11. 11. Analytical Studies Observational  Cross-sectional  Case-control  Cohort Experimental
  12. 12. Cross-sectional studies Characteristics  Data collected at single point of time  Describes associations  Prevalence Strengths  Quick  Cheap Weaknesses  Can’t establish cause-effect
  13. 13. Case-Control Study Start with people who have disease Match them with controls that do not Look back and assess exposures
  14. 14. Case-Control Study:Strengths Good for rare outcmes Can examine many exposures Useful to generate hypotheses Fast Cheap Provides Odds Ratio
  15. 15. Case-Control Study:Weaknesses Cannot measure  Incidence  Prevalence  Relative Risk Can only study one outcome High susceptibility to bias
  16. 16. Cohort Study Begin with disease-free patients Classify patients as exposed/unexposed Record outcomes in both groups Compare outcomes using relative risk
  17. 17. Cohort Study: Strengths Provides incidence data Establishes time sequence for causality Eliminates recall bias Allows for accurate measurement of exposure variables Can measure multiple outcomes Can adjust for confounding variables Can calculate relative risk
  18. 18. Cohort Study: Weaknesses Expensive Time consuming Cannot study rare outcomes Confounding variables Exposure may change over time Disease may have a long pre-clinical phase Attrition of study population
  19. 19. Clinical Trials Randomized Double-blind Placebo-controlled
  20. 20. Randomized ControlledTrial Outcome Treatment Group Randomization No Outcome StudyPopulation Outcome Control Group No Outcome
  21. 21. Clinical TrialsStrengths:  Best measure of causal relationship  Best design for controlling bias  Can measure multiple outcomesWeaknesses:  High cost  Ethical issues may be a problem  Compliance
  22. 22. Clinical decisions Patient’s circumstances Evidence and wishes Clinical Audit Technology assessmentStrategies to Practice Economic Systematic Primaryimplement guidelines studies reviews studiesguidelines