Health Research
What is the placebo effect?

An expectation of an effect gives that
effect.
What can increase the placebo
effect?
Big pills - not little ones
 Colored pills - not white tablets
 Capsules - not tablets
 Two doses - not one
 Injection - not pill
 Surgery - not injection

Psychological treatments
subject to the placebo effect.
Counseling
 Hypnosis
 Biofeedback
 Relaxation training
 Massage
 Stress & pain management techniques

What can increase the placebo
effect?

Both patient and physician expectations
How effective is the placebo
effect?

It can potentially:
Reduce insomnia
 Decrease low back pain
 Lower high blood pressure
 Decrease burn pain
 Relieve knee pain with sham (false) surgery

How can we separate the
placebo effect from the real
treatment effect?

Double-blind design.
Research Methods:
Correlation studies
 Cross-Sectional studies
 Longitudinal studies
 Experimental designs
 Observational designs

Correlation studies
Show the degree of relationship between
two factors
 Cannot indicate cause and effect

Cross-Sectional VS
Longitudinal studies
Cross-sectional studies
 Compare two or more separate groups

Faster
 One point in time


Longitudinal studies
Compares one group over time
 Longer
 Follow participants over years

Experimental study
Can determine “cause”
 At least two groups

Experimental group
 Control group


Variables
Independent variable
 Dependent variable

Observational studies


Does not manipulate variables
Prospective


Follow disease-free population for years to see what
happens
Retrospective




Opposite approach
Find population with disease and look backward
“After the fact”
Comparison group is not a control group
• No random assignment
• May differ on other factors
Observational studies

Retrospective (Cont.)

Two groups
• One with subject variable
• (e.g Overweight)
• One without subject variable
• (e.g Not overweight)
• Measure dependent variable (eg. Smoking)

Looks for risk factors in a disease



Factors increasing chance of the disease
Demographic
Behavioral
The “gold standard” of scientific
research
Randomized
 Placebo-controlled
 Double-blind
 Used for:

Drug studies
 Effectiveness of psychological and
educational interventions

Psychometrics (psychological
tests) in research

Reliability




Consistent results
Test-retest
Inter-rater (Two or more raters = same results)
Validity



Measures what it is designed to measure
Criterion validity
Predictive validity