1. Clinical/Medical Research Designs
David M. Fresco, Ph.D.
Professor
Department of Psychological Sciences
Kent State University
Kent, Ohio, USA

2. A healthy lifestyle may be the key to a long life

3. Do Tibetans have a natural immunity to life style diseases?
For many years, Tibetans appeared to have an immunity to lifestyle diseases such as high blood pressure
Diet?
Exercise?
Adaptation to living at high altitude?
Since the Tibetan Diaspora to India, incidence of lifestyle diseases on the rise among ethnic Tibetans
There appears to be relatively less awareness and knowledge about these controllable conditions

4. Outline of this lecture
Using “lifestyle” diseases as an organizing principle:
Illustrating important research methodologies commonly used in by Western scientists that might shed light on the effects of lifestyle diseases
After, engage in a small group exercise to design methodologically sound studies to explore and interrogate the problems associated with lifestyle diseases among ethnic Tibetans within and outside of Tibet

5. The Scientific Method
Science is the pursuit of systematized knowledge through observation
Objectives
description
prediction
control
understanding

6. Study Designs From http://www.cebm.net/index.aspx?o=1039
Doesn’t include before and after studies
descriptive studies
case report, case series, qualitative study, cross sectional survey
show what’s happening in a population and in subgroups
analytic studies
examine effect of intervention (I)/exposure (E) on outcome (O)
compare frequency of outcomes in a comparison (C) group with frequency in intervention or exposed group to quantify effect
may be experimental or observational
Centre for Evidence Based Medicine, Oxford, UK cebm.net
Prospective
A prospective study watches for outcomes, such as the development of a disease, during the study period and relates this to other factors such as suspected risk or protection factor(s). The study usually involves taking a cohort of subjects and watching them over a long period. The outcome of interest should be common; otherwise, the number of outcomes observed will be too small to be statistically meaningful (indistinguishable from those that may have arisen by chance). All efforts should be made to avoid sources of bias such as the loss of individuals to follow up during the study. Prospective studies usually have fewer potential sources of bias and confounding than retrospective studies.
Retrospective
A retrospective study looks backwards and examines exposures to suspected risk or protection factors in relation to an outcome that is established at the start of the study. Many valuable case-control studies, such as Lane and Claypon's 1926 investigation of risk factors for breast cancer, were retrospective investigations. Most sources of error due to confounding and bias are more common in retrospective studies than in prospective studies. For this reason, retrospective investigations are often criticised. If the outcome of interest is uncommon, however, the size of prospective investigation required to estimate relative risk is often too large to be feasible. In retrospective studies the odds ratio provides an estimate of relative risk. You should take special care to avoid sources of bias and confounding in retrospective studies.  

7. The Correlational Method
The correlational method examines the relationship between or among two or more variables
The variables are assessed as they exist in nature (no experimental manipulation)
Correlational studies seek to determine the magnitude and direction of a relationship among variables
e.g. stress and body weight

8. How to Read a Correlation Coefficient

10. Observe or Conduct Experiment?
Observational
cross sectional, case series, case-control studies, cohort studies
identify participants
observe and record characteristics
look for associations
Experimental
before and after studies, comparative trials, (controlled or head to head), randomized trials
place in common context
intervene
observe/evaluate effects of intervention
experimental study
researcher manipulates exposure by allocating participants to intervention or exposure group
follow up under carefully controlled conditions. Controlled trials, when randomised and blinded, can control for biases
analytic observational study
case control, cohort, some cross-sectional studies
measure exposure in the groups
match groups of participants
assess associations between exposures and outcomes
Centre for Evidence Based Medicine, Oxford, UK cebm.net

11. The Survey Method Used in both descriptive and correlational research
Survey technique asks questions of large numbers of persons to gain information on attitudes and behavior
Two main approaches
Questionnaires
Interviews
Interview, mail, phone, internet, etc.

12. The Survey Method Pros: Good, cheap, anonymous, diverse population,
Easy to get random sampling (a sampling that represents your population you want to study)
Cons:
Low Response Rate
Sampling issues
People may not respond accurately
People Lie or just misinterpret themselves
Wording Effects

13. Random Sampling

14. The Cross-sectional Method
Snap shot
Measure exposure and outcome variables at one point in time
Main outcome measure is prevalence at this point in time
NB Prevalence versus incidence (get over time)
Relative prevalence - prev in group with RF compared to those without,

15. Cross-sectional Study
What is the current prevalence of lifestyle diseases among ethnic Tibetans?
Image from

16. Cross-sectional Study: Strengths
Generalizable results if sample reflects the whole population
Can study multiple outcomes and exposures
Immediate outcome assessment and no loss to follow-up, therefore faster, cheaper, easier
Can measure prevalence
Hypothesis generating for causal links
Serial surveys to avoid learning effect from baseline measurement with cohort study

17. Cross-sectional Study: Weaknesses
Provides limited information
Cannot establish sequence of events
establishes association at most, not causality
Impractical for rare diseases
Prone to bias
recall bias
social desirability bias
Serial surveys to avoid learning effect from baseline measurement with cohort study

18. Variation on Cross-sectional design with Prospective Assessment
Image from
Time
Present (Red = risk factor present)
Future (Red = develops disease)

19. The Experiment
The experiment allows for determination of a causal relation between two or more variables
An experiment involves
random assignment of subject to experimental conditions
manipulation of an independent variable (IV: believed to be a causal variable)
measurement of a dependent variable (DV is assumed to the controlled by the IV)

20. Experimental Study Vocabulary
Independent Variable (IV)
Factor that is manipulated
Dependent Variable (DV)
Factor that is measured
Extraneous Variables
Factors that effect DV, that are not IV
Experimental Group
Group exposed to IV
Control Group
Group not exposed to IV
Placebo
Inert substance that is in place of IV in Control Group

21. Randomized Controlled Trial (RCT)
True experimental design
Participants assigned by chance, following consent, to one of at least two conditions
Key features of classic experimental design:
Random assignment
determines who assigned to which group
Pre & post tests
outcome measured before & after intervention
Control group
same experiences as experimental group except no exposure to experimental stimulus

22. Randomized Controlled Trial (RCT)
Study designs
Centre for Evidence Based Medicine, Oxford

23. Randomized Controlled Trial (RCT)
Study designs
Centre for Evidence Based Medicine, Oxford

24. Pros and Cons of RCT Advantages
Can establish causal relationship between IV and DV
Unbiased distribution of extraneous variables
Randomization facilitates statistical analysis
Disadvantages
Expensive: time and money
Volunteer bias
Ethically problematic at times
Study designs
Centre for Evidence Based Medicine, Oxford

25. Your Assignment

26. Your Group Assignment
Using the materials provided, design four studies that will help us understand the impact of lifestyle diseases on ethnic Tibetans living in India
Survey study
Cross-sectional study
Prospective study
RCT

27. Survey Study
Main Question: What is the current prevalence of lifestyle diseases among ALL ethnic groups in India?
Secondary Question: How much knowledge of life style diseases do residents of India possess?
Assignment
Design a survey study to address these questions
Give consideration to sampling (e.g., random vs. volunteers)
Give consideration to recruitment strategies and formats for completing assessments

28. Cross-sectional Study
Main Question: What is the association of lifestyle risk factors (e.g., diet, exercise, smoking, etc.) to current prevalence of lifestyle diseases among ethnic Tibetans in India?
Secondary Question: Is knowledge of lifestyle diseases associated with lower rates of actual lifestyle diseases once they are formally assessed?
Assignment
Design a cross-sectional study to address these questions
Give consideration to recruitment strategies and formats for completing assessments

29. Prospective Study
Main Question: Among ethnic Tibetans, what is the association of current lifestyle risk factors (e.g., diet, exercise, smoking, etc.) and protective factors (e.g., knowledge of lifestyle diseases) on the likelihood of developing lifestyle disease in the future
Assignment
Design a prospective study to address these questions
Give consideration to recruitment strategies and formats for completing assessments
Hint: Consider creating subgroups (e.g., high risk/low knowledge, high risk/high knowledge, etc.)

30. RCT Study
Main Question: Can a program of diet and exercise help reverse or control the effects of lifestyle diseases among ethnic Tibetans who have or are at risk for lifestyle diseases?
Secondary Question: Drawing on your knowledge of Tibetan and Indian culture, what are the challenges in persuading participants to remain adherent to the diet and exercise regimen?
Assignment
Design a RCT to address these questions (e.g., Treatment vs. Control or Treatment versus Placebo, etc.)
Give consideration to recruitment strategies and formats for completing assessments
Give consideration to describing ways to tailor a program consisting of diet and exercise to make the program maximally appealing to ethnic Tibetans