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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: – 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: • • • • • Correlational studies Cross-Sectional studies Longitudinal studies Experimental designs Ex Post Facto designs Correlational 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 Ex Post Facto designs • “After the fact” • Does not manipulate variables • Two groups – One with subject variable • (e.g Overweight) – One without subject variable • (e.g Not overweight) – Measure dependent variable (eg. Smoking) Ex Post Facto designs • Comparison group is not a control group – No random assignment – May differ on other factors Research Methods in Epidemiology • Epidemiology = study of epidemics ( eg. AIDS) • Risk factors – Demographic – Behavioral • Prevalence – Portion of population with disease • Incidence – New cases in a year Observational studies • Prospective – Follow disease-free population for years to see what happens • Retrospective – Opposite approach – Find population with disease and look backward 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 • Validity – Measures what it is designed to measure – Criterion validity – Predictive validity