1. Quantitative Design Descriptive, Correlational and Comparative

2. Session Objectives Choosing the correct quantitative methodology A History of quantitative research What type of research should I be doing? Descriptive research Correlational research Experimental research Related and unrelated designs Randomisation and controls Blinding / ITT / Time periods

3. Involve “We believe that involving members of the public leads to research that is: more relevant to people’s needs and concerns more reliable more likely to be used” http://www.invo.org.uk

5. Session Objectives Choosing the correct quantitative methodology A History of quantitative research What type of research should I be doing? Descriptive research Correlational research Experimental research Related and unrelated designs Randomisation and controls Blinding / ITT / Time periods

6. A History of Quantitative Reasoning Positivism Empiricism Deduction and Induction Hypothetico-deductive model

7. Reject / modify theory Falsification Deduction Test Hypothesis Hypothesise Generalise Describe Measure Observe

8. Session Objectives Choosing the correct quantitative methodology A History of quantitative research What type of research should I be doing? Descriptive research Correlational research Experimental research Related and unrelated designs Randomisation and controls Blinding / ITT / Time periods

9. Am I… Using numbers from outcomes Comparing the effectiveness of two treatments Determining relationships between two variables Monitoring the progress of a group of patients Using text / pictures / objects Seeking opinions Observing human behaviour (immersing myself) Exploring subjective meanings / phenomena Quantitative Research Qualitative Research Then I’m doing…

10. Session Objectives Choosing the correct quantitative methodology A History of quantitative research What type of research should I be doing? Descriptive research Correlational research Experimental research Related and unrelated designs Randomisation and controls Blinding / ITT / Time periods

11. Choosing the correct research method Alternatives:- Descriptive studies Correlation studies Experimental studies

12. Allocate the research method to these studies Do patients with greater ventilatory defects experience more fatigue after stroke? How many patients with stroke suffer from fatigue? Do interventions to increase ventilatory capacity reduce fatigue? What is the size of the ventilatory defect after stroke?

13. Session Objectives Choosing the correct quantitative methodology A History of quantitative research What type of research should I be doing? Descriptive research Correlational research Experimental research Related and unrelated designs Randomisation and controls Blinding / ITT / Time periods

14. Descriptive studies Clear, specific, measurable definition of the disease/condition Least-publishable medical literature Feedback to those who need to know Important for: Trend analysis Healthcare planning Hypothesis generation Do not over analyse!

15. NICE levels of evidence Level Type of evidence Ia: Evidence from meta-analysis of randomised controlled trials Ib: Evidence from at least one randomised controlled trial IIa: Evidence from at least one controlled study without randomisation IIb: Evidence from at least one other type of quasi-experimental study III: Evidence from non-experimental descriptive studies, such as comparative studies, correlation studies and case-control studies IV:Evidence from expert committee reports or opinions and/or clinical experience of respected authorities

16. Session Objectives Choosing the correct quantitative methodology A History of quantitative research What type of research should I be doing? Descriptive research Correlational research Experimental research Related and unrelated designs Randomisation and controls Blinding / ITT / Time periods

17. Correlational research Investigate the relationship between variables Use one randomly selected group Use two variables – both measurable (interval level) It does not tell us the cause of the relationship

18. Correlation studies Relationship between A and B Positive correlation (1.0)Negative correlation (-1.0)

19. Session Objectives Choosing the correct quantitative methodology A History of quantitative research What type of research should I be doing? Descriptive research Correlational research Experimental research Related and unrelated designs Randomisation and controls Blinding / ITT / Time periods

20. The “classic experimental design” Must include: 2 or more differently treated groups (treatment & control) Random allocation (chance assignment) If design does not satisfy both of the above it is described as Quasi-experimental

21. An experiment Controlled conditions Monitor an ‘effect’ Manipulation of an experimental variable Experimental group Control group Minimisation of: Systematic errors (bias) Random errors (chance) Independent variable

22. Session Objectives Choosing the correct quantitative methodology A History of quantitative research What type of research should I be doing? Descriptive research Correlational research Experimental research Related and unrelated designs Randomisation and controls Blinding / ITT / Time periods

23. Experimental Design Terminology: –Related / within / same subject design Types : –Within subject studies –Participants as own control

24. Within subject studies Using different limb as a control Examples: Injured vs. uninjured limb Left vs. right Dominant vs. non-dominant measure Interventionmeasure Treatment phase (B)

25. Participants as own control Using same limb as control measure Control phase (A) Treatment phase (B) measure A B A

26. Draw a flow chart for the following related-subject studies: 1.Will the single-leg vertical hop test determine differences between lower limb dominance? 2.Validity of the 6 minute walk test for assessing HR recovery after an exercise-based cardiac rehabilitation programme

27. Experimental Design Terminology: –Unrelated / between / different-subject design Types: –Matched design –Crossover design –Factorial design –RCT

28. Matched designs 2 or more groups Subject matched on ‘x’ variable(s) May or may not be randomised to groups Disadvantages Can only match a few variables at a time May miss more important variables Has implications for analysis – unrelated independent tests

29. Crossover design Control Treatment Control Group 1 Group 2 Measure

30. Factorial design Resistance Age>40 <40 Group 3 Group 4 Group 2 Group 1 180  /sec320  /sec Factors: major independent variables Factor subgroups 2X2 design

31. Draw a flow chart for the following unrelated-subject studies Is the production of sputum dependent on type or duration of exercise in patients with cystic fibrosis? The effects of an early or delayed strengthening regime following ACL reconstruction surgery Quadriceps muscle strength is different for Asian, Caucasian and African-Caribbean children

32. Session Objectives Choosing the correct quantitative methodology A History of quantitative research What type of research should I be doing? Descriptive research Correlational research Experimental research Related and unrelated designs Randomisation and controls Blinding / ITT / Time periods

33. The randomised controlled trial Random allocation Similar groups Double blind Control group Numerical outcomes Intention to treat (ITT) Standardised procedures

34. Random allocation Unrestricted allocation Tossing a coin Random number tables Stratified randomisation Cluster randomisation Block randomisation

35. Allocation to groups – other methods Alternative Matching – max 3 variables Specification – similar to matching Minimisation

36. Controls Place the following in the order of importance (1 = true experimental) Literature No treatment Placebo Standard treatment Historical Own control

37. Session Objectives Choosing the correct quantitative methodology A History of quantitative research What type of research should I be doing? Descriptive research Correlational research Experimental research Related and unrelated designs Randomisation and controls Blinding / ITT / Time periods

38. Blinding Double blind Therapist and / or researcher Participant Single blind Therapist and / or researcher Very difficult to double blind in clinical research

39. Intention to treat (ITT) Sample attrition Death Dropout Missing data Refusal to be randomised ITT = Unbiased comparison of randomised groups regardless of the intervention

40. Time periods of study Cross sectional Measurement taken at one point in time Prospective longitudinal Retrospective Historical

41. Advantages of experimental design Randomisation minimises the risk of extraneous variables confounding results Control over the independent variable allows clear understanding of cause and effect Pre- and post-testing controls for time-related threats to validity Allows for powerful statistical manipulation Will reveal causal relationships

42. Disadvantages of experimental design Difficult to represent specified population Difficult to choose control Difficult to control extraneous variables Natural environment not always achievable Patient adopts unnatural role Design lacks diversity of e.g. MDT roles