research methods quantitative research by dr viv rolfe n.
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RESEARCH METHODS Quantitative Research by Dr Viv Rolfe

RESEARCH METHODS Quantitative Research by Dr Viv Rolfe

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RESEARCH METHODS Quantitative Research by Dr Viv Rolfe

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  1. RESEARCH METHODS Quantitative ResearchbyDr Viv Rolfe Evidence Based PracticeThe University of Nottingham School of Nursing

  2. Dr Vivien Rolfe BSc PhD • 20 Year research career • Degree - Physiology • PhD - Diarrhoeal diseases • Research - Inflammatory bowel disease (Great Ormond Street) • Research - dog and cat nutrition (Mars UK) • Market research – qual and quant (Mars UK) • Lecturer - University of Nottingham

  3. Ice Breaker + Needs from today (5mins) • Do they know eachother? • Everyone say your name, where from and something about yourself. • What do they want out of today? • Write on board.

  4. Plan of Today • Introduction to research • Qual versus quant • Types of quantitative research

  5. Research is….. • inquiring into, finding out • a systematic investigation to establish facts • a search for knowledge • “original investigation undertaken in order to gain knowledge and understanding.” Dept. For Employment and Learning & HEFCE (Higher Education Funding Council for England)

  6. Health and Medical Research • Research is fundamental to advancing healthcare and medicine. • Produces new treatments and drugs. • Advances understanding of new diseases and problems (obesity, aging, CJD, MRSA…all topical). • Can help determine best type of care. • Can help evolve patient services. • Development of diagnostic tests. • Development of prognostic markers.

  7. UK Medical Research Priorities • DOH - £540m in 2002-2003 • cancer, mental health, coronary heart disease (CHD) • ageing and older people, public health, genetics , diabetes.

  8. Think about research? (5 minutes in pairs) • List some different types of research you are aware of. • Who does it? • What is it? • Write ideas on post it notes and cluster (hopefully into QUAL and QUANT).

  9. Research – from dream to reality RESEARCH PLAN What? Which? Who? What am I looking at? Which methods to use? Who am I investigating? IDEA Hypothesis Literature review Dissemination Funding Ethics Implementation Conduct Research Data analysis Conclusions

  10. Qualitative versus Quantitative QUANT QUAL Focus Big picture Tests ideas and theories Generates ideas and theories Quantify - measure Opinions, feelings Objective Subjective (opento personal interpretation) Numbers and statistics Words “verbatims”

  11. Quantitative Research “a formal, objective, systematic process in which numerical data are utilised to obtain information about the world“

  12. Types of QUANT Non-experimental Case study Cross sectional Cohort/longitudinal Case control Correlational Descriptive Survey Epidemiology Needs assessment Information gatheringabout populations. Experimental Human clinical trial Veterinary clinical trial Animal experimentation In vitro laboratory All test a hypothesisabout an intervention,technique, practice,service.

  13. Types of QUANT Study Design 4 main types: • Clinical trials (from crap to RCT) • Cohort studies • Case-control studies • Cross-sectional studies

  14. Clinical Trials

  15. Clinical Trial • Experimental research testing the effectiveness of an intervention on a sample of human subjects. • Called intervention trials. • Clinical research usually stems from laboratory-derived ideas and hypotheses: • In vivo – whole body • In vitro – test tube

  16. What happens in a Clinical Trial? • People usually do have a disease or illness at the study beginning, they are observed to see the treatment/intervention is having an EFFECT.

  17. “I’m designing a clinical trial and I’ve picked….” Fred, Harry, Mavis, Bert, Daisy Tom, Betty, David, Edna, Bill Treatment e.g. brushing teeth using fluoride toothpaste No Treatment Measure and compare: e.g. number of fillings over a year

  18. What do you notice about this study? • A and B subjects are hand-picked • small numbers (10’s) • the groups are different • the study is not blind • there is no placebo • it is one phase (single leg)

  19. Pitfalls to Overcome THE PEOPLE • A and B subjects are hand-picked - researcher could manipulate the outcome of the research so introduce BIAS (unfairness) • The group numbers are small – you must complete a POWER CALCULATION to see how many subjects to use, otherwise statistical analysis will be problematic. • The groups are different - one contains children and the other doesn’t, so we are not comparing like with like. Groups must be MATCHED. THE DESIGN • The study is not blind - means the clinical staff and patients know who is in what group, which causes BIAS. • There is no placebo - or “dummy”, so no adequate control. • The design has only one leg (ONE PHASE) so may be susceptible to differences due to TIME.

  20. Creating a Robust Trial A and B subjects are hand-picked small numbers; not matched, not blind, no placebo; one phase (single leg) A and B are randomly chosen Groups are matched (age, sex, other) Single blind (patient doesn’t know) Placebo controlled Double blind (patient and clinician don’t know) Cross-over Multi-centre (UK, International) • Pilot study • Not robust evidence • Used to get funding/ • interest for a larger • study • Large-scale study • Evidence to inform • clinical/health • care decisions

  21. How could you improve the study? • 10 minutes in groups • What do you want to look at? • Who would you use? • What would you measure?

  22. Ideal Study Toothpaste + placebo Toothpaste + fluoride Cross-over e.g. if study done at Easteror Xmas, timewill be aninfluence!. measurement measurement Toothpaste + fluoride Toothpaste + placebo Randomly chosen Larger numbers Matched Double blind measurement measurement

  23. Multicentre!

  24. Conclusions Randomisation - the random assignment of subjects to treatment groups Double-blind - neither the researcher or the subjects know which are the experimental group or control group Placebo-controlled Cross-over (may be constrained by ethics,but better if each subject acts as their own control which can reduce sample size – butneed a “washout phase” and not appropriate if treatment gives permanent effects) Multi-centre (may be costly and timely)

  25. What to Look for in a Good Trial….. • Look for these words in the methods section… • Randomised-controlled trial (RCT) • Double-blind randomised-placebo-controlled trial – THE BEST. • RCT’s follow standardised procedures to ensure good scientific standard.

  26. Sources of RCT evidence • • Cochrane Database of Systematic Reviews

  27. BREAK?10.30 – 10.45

  28. Non-experimental QUANT The 3 C’sCross-sectionCohortCase-control Effectiveness of diagnosis or screening Aetiology or prognosis Aetiology or prognosis for a rare condition

  29. Cross-Sectional Study

  30. Cross-sectional Studies • Look at a relationship in a defined group at ONE POINT IN TIME (not over a period of months/years). • Used for testing the effectiveness of diagnostics or screening, or tests for the prevalence of a disease or parameter. • May measure a physiological parameter/do a scientific test. • Give valuable insight into whether a practice/test needs to be modified to improve health care.

  31. Example 1 Tanning is associated with optimal vitamin D status and higher bone mineral density.

  32. The Methods • Why – Vitamin D is made in the skin in sunlight, so do people who use sunbeds have higher concentrations of vitamin D? • What – a cross-sectional analysis of sunbed and non-sunbed users. • Who – 50 people who use sunbeds weekly and 106 control non-users. • How – compare blood Vitamin D levels, and bone mineral density testing.

  33. The Results • Tanning bed users had 90% higher blood vitamin D levels compared to controls. • Tanners had significantly higher bone mineral density scores.

  34. The Conclusions • Regular use of a tanning bed can benefit the skeleton. • OK, there are obvious known additional risks of skin cancer, but this study indicates that sun beds may be of therapeutic use for some conditions.

  35. Strengths and weaknesses • Cheap and simple • Ethically safe BUT • Establishes an association/relationship between things (UV rays and Vitamin D), but but not causes • If it relies on questionnaires, patient recall of events may introduce bias susceptibility

  36. Cohort Study

  37. Cohort Studies • “Cohort” means group of individuals with similar traits… • e.g. same age • support same football team (West Ham of course) • who all have eczema

  38. Why do a cohort study? • Often carried out to study harmful interventions (like smoking) which would not be ethically permitted in a clinical study. • To see what risk factors contribute to a disease, or see what their outcome or PROGNOSIS is in the future. • These are longitudinal studies – over a period of time.

  39. Design • Can be prospective - look forward, to look at if a disease develops, or the outlook/prognosis if the disease is already there. • Can be retrospective - look backward, to examine the history of a disease, and find risk factors associated with it.

  40. Retrospective cohort study What were they exposed to? Clinical Records Or Questionnaires 1995 - 2005 JANUARY 2005 Disease Risk factors Possible causes

  41. Example 2 A high morbidity outbreak of MRSA among players on a college football team.

  42. The Methods • Why - MRSA infections in football are an increasing problem. • What - A retrospective cohort study was carried out to see what factors were contributing to the infections. • Who – cohort of 200 football players with skin abscesses or infection were studied. • How – their habits/ behaviours/ recorded.

  43. The Results – the risk factors • The incidence of infection differed depending on the players position (and whether he had more knocks and bumps). • Turf burns enhanced the risk. • Body shaving enhanced the risk. • Sharing the Jacuzzi at the end of the match showed a small increase in risk of developing infection.

  44. The Conclusions • Educate players to reduce body shaving before a game. • Improve padding to prevent turf burns. • Introduce means of sterilising Jacuzzi water, just as an additional precaution. • Probably can’t do much about playing positions.

  45. Prospective cohort study JAN 2005 JAN 2005 – JAN 2006 No Disease Disease Prognosis/outcome Assessment of risk factors (environment, lifestyle) Can be clinical measure or a questionnaire

  46. Example 3 Female-male infectivity of HIV among circumcised and uncircumcised Kenyan men.

  47. The Methods • Why - HIV infection leading to AIDS is a major cause of mortality in Africa (and other countries). Observations suggest that circumcision reduces HIV infectivity. • What – a prospective cohort study was carried out. • Who - 745 Kenyan truck drivers. • How – sexual habits were recorded at interview and follow up interviews.

  48. The Results • Prognosis - after intercourse the probability of contorting aids was high. • Infectivity was higher for uncircumcised men compared to circumcised men.

  49. The Conclusions • Lack of circumcision does appear to be a risk factor in AIDS transmission. • Encourage circumcision if culturally possible, or promote awareness of this fact to modify sexual behaviour.