RESEARCH METHODS Quantitative Research by Dr Viv Rolfe

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RESEARCH METHODS Quantitative ResearchbyDr Viv
Rolfe

• Evidence Based PracticeThe University of
  Nottingham
• School of Nursing

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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

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(No Transcript)
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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.

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Plan of Today

• Introduction to research
• Qual versus quant
• Types of quantitative research

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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)

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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, MRSAall topical).
• Can help determine best type of care.
• Can help evolve patient services.
• Development of diagnostic tests.
• Development of prognostic markers.

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UK Medical Research Priorities

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

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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).

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Research from dream to reality
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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
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Quantitative Research
a formal, objective, systematic process in which
numerical data are utilised to obtain information
about the world
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Types of QUANT
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Types of QUANT Study Design

• 4 main types
• Clinical trials (from crap to RCT)
• Cohort studies
• Case-control studies
• Cross-sectional studies

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Clinical Trials
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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

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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.

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Im designing a clinical trial and Ive 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
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What do you notice about this study?

• A and B subjects are hand-picked
• small numbers (10s)
• the groups are different
• the study is not blind
• there is no placebo
• it is one phase (single leg)

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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 doesnt, 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.

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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 doesnt know) Placebo
controlled Double blind (patient and clinician
dont 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

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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?

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Ideal Study
Toothpaste fluoride
Toothpaste placebo
Randomly chosen Larger numbers Matched Double
blind
measurement
measurement
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Multicentre!
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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)

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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.
• RCTs follow standardised procedures to ensure
  good scientific standard.

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Sources of RCT evidence

• www.nelh.co.uk
• Cochrane Database of Systematic Reviews

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BREAK?10.30 10.45
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The 3 CsCross-sectionCohortCase-control
Non-experimental QUANT
Effectiveness of diagnosis or screening
Aetiology or prognosis
Aetiology or prognosis for a rare condition
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Cross-Sectional Study
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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.

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

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The Results

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

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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.

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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

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Cohort Study
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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

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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.

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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.

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Retrospective cohort study
Risk factors Possible causes
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Example 2 A high morbidity outbreak of MRSA among
players on a college football team.
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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.

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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.

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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 cant do much about playing positions.

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Prospective cohort study
Assessment of risk factors (environment,
lifestyle) Can be clinical measure or a
questionnaire
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Example 3 Female-male infectivity of HIV among
circumcised and uncircumcised Kenyan men.
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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.

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The Results

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

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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.

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Strengths of Cohort Studies

• Looks at more than one influence or factor
  compared to clinical trial that just studies one
  (e.g., using the Jacuzzi, turf burns, players
  game position).
• Provides rich information about lifestyle and
  health associated RISK FACTORS.
• Ethically safe (i.e. not inflicting treatments on
  people).
• Easier and cheaper than an RCT.

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Weaknesses of Cohort Studies

• In order to observe any statistical and
  biological effects it is often necessary to study
  large groups.
• Large studies are costly and timely, particularly
  the prospective ones.
• Blinding is difficult i.e. the subjects know
  what group they belong to, so is often best not
  to tell them the nature of the study.
• No good for rare diseases where large groups
  dont exist.
• Often relies on peoples recollections.

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Case Control Study
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Case-control studies

• Similar to cohort in being able to identify
  risks.
• Rather than looking at random groups, smaller
  numbers of patients (cases) are chosen along with
  a CONTROL.
• Because patients are chosen, this can introduce
  bias either from who is selected, and how the
  measurements are taken.
• However, you can focus in on rare cases or
  situations.

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Case control studies

• Answers the question what makes a group of
  individuals different in terms of the causes of a
  disease?
• Design Can be prospective or retrospective
  looking back at medical history.
• Needs 2 groups - Compares those with the disease
  with a control group of people with similar
  characteristics (but no disease).

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Example 4 Diet and stomach cancer a case-control
study in South India.
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The Methods

• Why - the prevalence (occurrence) of stomach
  cancers in some parts of India is increasing. It
  is not known what factors are associated with
  this.
• What a prospective case-control study monitored
  the risks of developing stomach cancer.
• Who - 194 patients and a matched (age, sex,
  religion) healthy control group for 3 years.
• How interviews using questionnaire.

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The Results

• A questionnaire collected data on food intake,
  socio-demographic factors and other behaviours
  such as smoking.
• Risk of cancer was high for those eating spicy
  food, consuming chilli, and consuming high
  temperature food.

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The Conclusions

• Some interesting associations have been found
  between diet and cancer.
• Further studies are needed to see whether there
  is a definite link between spicy food and stomach
  cancer (ie now go back to the lab and test this
  hypothesis).

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Strengths and weaknesses

• Quick and cheap
• The only feasible method for very rare disorders
  fewer subjects needed than cross-sectional
  studies
• BUT
• Often relies on recall to determine result
• Difficult to select a control group which may
  introduce bias

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Types of Quantitative Research

• 4 main types
• Clinical trials (from crap to RCT)
• Cohort studies
• Case Control study
• Cross-sectional studies

summary
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Activity in groups
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• From the handout distinguish which of the
  following are
• 1. Clinical trial (is it a good or bad one?
• 2. Cohort studies
• 3. Case control studies
• 4. Cross-sectional studies

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Additional Resources
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Studies Cited in this Course
Tangpricha V, Turner A, Spina C et al. Tanning is
associated with optimal vitamin D status (serum
25-hydroxyvitamin D concentration) and higher
bone mineral density. Am J Clin Nutr, 2004,
80(6), 1645. Begier EM, Frenette K, Barrett NL
et al. A high-morbidity outbreak of MRSA among
players on a college football team, facilitated
by cosmetic body shaving and turf burns. Clin
Infect Dis, 2004, 1539(10), 1446. Mathew A,
Gandadharan P, Varghese C et al. Diet and stomach
cancer a case-control study in South India. Eur
J Cancer Prev, 2000, 9(2), 89. Baeten JM,
Richardson BA, Lavreys L et al. Female-to-male
infectivity of HIV-1 among circumcised and
uncircumcised Kenyan men. J Infect Dis, 2005,
15191(4), 546.
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Useful Weblinks
Medline the one-stop resource for all global
medical and health research. For example to find
a type of study type in case control cohort,
etc. You can alsouse the limits button to
search for an RCT or a particular population
group.
http//www.ncbi.nlm.nih.gov/entrez/query.fcgi
http//www.clinicalevidenceonline.org/
http//www-phm.umds.ac.uk/teaching/ClinEpid/Observ
S.htmcase-control
http//www.cebm.net/study_designs.asp
http//medicine.ucsf.edu/resources/guidelines/user
s.html
http//symptomresearch.nih.gov/tablecontents.htm
http//www.shef.ac.uk/scharr/ir/netting/
http//www.mja.com.au/public/issues/174_05_050301/
craig/craig.html
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Glossaries of Research Terms
For quick reference to research terms such as
prognosis, prevalence, subjective, cohort,
cross-section, statistics, then go to
http//www.mori.com/rmu/glossary.shtml
http//www.fortunecity.com/greenfield/grizzly/432/
rra2.htmexperiment
http//www.cebm.net/glossary.asp
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Prevalence

• Measure of a condition in a population
• At a point in time
• Over time (e.g. 1 year)
• Gives an indication of the extent of a problem
  and health care requirements.

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Incidence

• Number of new occurances of a condition
• over time (e.g. 1 year, 10 years.)
• Gives an indication of the extent of a problem
  and health care requirements.

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Prevalence 4 out of 20 20 in the last 10 years.
1995 - 2005
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Experimental
Non-experimental
Intervention of drugor practice
Diagnosis or Screening test
Aetiology (causes)
Prognosis (outlook)
Summarise your own learning here..
Cohort (case controlfor rare groups)
Cohort (case controlfor rare groups)
Cross-sectional study
Clinical trial RCT
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Session Feedback for Viv Rolfe, EBL Course,
Monday 24th January
Please tick which box you think (1 strongly
agree to 5 strongly disagree)
Content

• 2 3 4 5

Strongly agree
Strongly disagree
a) The course content reflected the aims andthe
expected learning outcomes.
b) The pace was about right.
c) The strong points of the course were (please
indicate)
d) The weak points of the course were (please
indicate)
Lecturer

• 2 3 4 5

Strongly agree
Strongly disagree
a) She was knowledgeable
b) She could answer questions satisfactorily
c) She/the course kept my attention.
d) I felt able to participate.
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Session Feedback for Viv Rolfe, EBL Course,
Monday 24th January
Please tick which box you think (1 strongly
agree to 5 strongly disagree)
Event Materials

• 2 3 4 5

Strongly agree
Strongly disagree
a) The handouts complemented the course.
b) The handouts aided understanding.
c) I shall use the website.
Overall

• 2 3 4 5

Strongly agree
Strongly disagree
a) The course was useful.
b) Please rate you understanding/level of
knowledge on the subject of research methods
Before today
Low 1 2 3 4 5 High
After today
Low 1 2 3 4 5 High
c) Any other comments
thankyou!
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Website and contact details
Additional information, links to the
glossariesand other websites mentioned can be
found on Vivs website www.nottingham.ac.uk/nqzv
r/teaching.htm Password is einstein You can
also contact me by email if you have any further
questions orcomments Vivien.rolfe_at_nottingham.ac.
uk