2. Research Methods Objectives –Understanding sampling –Understanding different research designs –Understanding strengths and weaknesses of different designs –Understanding difficulties of subluxation research

3. *PURPOSE OF Experimental RESEARCH DESIGN *To help the researcher answer the research question. *“To control for possible rival hypotheses or extraneous variables that might compete with the independent variable as an explanation for the cause-effect relationship.”

4. *Subjects/Sampling *Sampling process includes two steps *Choosing the subjects to be included in the study *Determining which subjects receive treatment

5. *Sample *Must define the POPULATION. The more a definition is limited, the less applicability to the general population. *A SAMPLE is a portion of the population investigated to draw conclusions about the entire population *Sampling is used because it is not practical to use the entire population

6. *Sampling Bias *Occurs when one of the two (or three) study groups differ in one or more variables that would affect the outcome of the study. *Choosing a sample that is not reflective of the target population of the treatment

7. “ Reporting of age data in clinical trials of arthritis. Deficiencies and solutions” Arch Intern Med 1993:153:243-8 Review of 73 studies 9664 patients 2.1% of sample of was over age of 65 62% of NSAID are consumed by population over 65. Older people more likely to have adverse reactions In order to keep side effects minimal, older people excluded.

8. *Types of Samples *Convenience *Random *Definition: each member of the population has an equal opportunity to be included in the study

9. *Types of Random Samples *Simple random sampling *Stratified random sampling *Cluster sampling

10. *Simple random sampling *Purest form of sampling, but not necessarily the best. After defining the population each individual is randomly assigned a group.

11. *Stratified random sampling *Used when certain characteristics of a population exhibit established proportions.

12. *Cluster sampling *Gives everyone within a population an equal chance of being chosen for the study *But subject to sampling error at each stage of clustering

13. *Random Sampling Methods *Table of random numbers *Computer generated numbers *Draw straws, marbles, etc.

14. *Sample size *The larger the sample the easier it is to measure small but significant effects *If the effects of the study are to be great, a smaller sample size could be used *If using parametric tests you need at least 30 subjects in each subgroup

15. Classifications of Research Design Pre-experimental Quasi-experimental Experimental

16. Pre-experimental (Descriptive) Purpose is to observe and describe Does not offer explanations, provide causes or provide evidence May lead to additional research

17. Types of pre-experimental design Surveys Case reports Case series Historical research

18. Case Reports Not experimental and can not prove anything, but still very important AIDS, Lyme disease first described as a case reports X----------------O X is the independent variable (treatment) and O is the observation of the dependent variable (blood pressure, weight, pain)

19. Case Series Also known as “one group pretest-posttest design” Same as case report but uses a group O--------------X-------------O

20. Pre-experimental design Strengths –Inexpensive –Relatively easy to perform Weaknesses –Minimal controls –Cannot show contributory cause

21. Quasi-Experimental Designs Characterized by moderate controls Non-equivalent control group design O----------X-----------O O-----------------------O

22. Quasi-experimental design Strengths –Relatively easy to perform –Less expensive than experimental design Weakness –Moderate controls –Cannot show contributory cause

23. True experimental design Use of strong controls Random assignment to groups Manipulation of the independent variable R-----O-----X-----O R-----O------------O

24. Experimental design Strengths –Strong controls –Can show contributory cause Weaknesses –Expensive –Difficult to perform –Ethical issues relating to control group –Participant recruitment often a problem

25. Other Forms of Research Meta Analysis (Putting together the data from various RCT’s) Qualitative studies (Objective study of the human experience using nonstatistical analysis)

26. Other common design terms Cross-sectional study –Measurement of presumed cause and effect at the same time –Capable of measuring prevalence (proportion of pop. with outcome at one point in time) Doctor visit common prior to ones death. Is the doctor visit a risk factor? Cross-over design: treatment group and control group switch roles

27. Other common design terms Longitudinal Study: carried out over time Retrospective: Grouping by presence or absence of outcome and review of past history –Hypertension study grouped by outcome, presence or absence of hypertension Prospective : Observations made over a period of time as the events occur –A RCT is a longitudinal prospective study

28. The Case Report

29. Objectives Understand the importance of the case report in biomedical literature Know different designs of case reports Understand the structure of the case report and the elements of each section

30. Hierarchy of Knowledge Randomized Clinical Trial Clinical trials Case Series Case Studies Antedotal Reports Testimonials Observations Rumors/Assertions.

31. In 1985 the Journal of the American Medical Association republished 51 landmark articles to mark it’s first century of publication. 5 of the 51 were case reports. 20% to 30% of research articles involve less than 10 subjects.

32. A case report is…. “biomedical story-telling” delivery vehicle for clinical education stimulant for more comprehensive and prospective research.

33. A case report is not…. Antedotal A Testimonial A testimonial without sensationalism An advertisement….. Although it sometime is.

34. Types of Case Reports Descriptive: Purely descriptive of a condition or situation Interventive: Involves intervention on the part of the treating doctor.

35. Case Report Design One shot case study –Intervention then outcome assessment Pre-test, post-test design –Initial measurement, intervention, outcome measurement Time-series (A-B-A) –Repeated measurements on and off treatment.

36. Case Series Variation on solitary case report Multiple individuals with same diagnosis and treatment being studied Each case may be separately described or lumped together with data summaries.

37. Structure Abstract Introduction Case Report Discussion Conclusion References.