1. How Effective are Behaviour Change Interventions? Contents: 1.How do we measure effectiveness? 2.How effective is medical therapy? 3.How effective are psychological therapies?

2. “Effect Size” A standardized statistic to show the impact of treatments (Mean result for treatment group – mean for controls) / standard deviation Interpretation: An effect size of 0.5 represents a success rate of 65% in the treatment group, and 35% in the control group (“success” = score above overall median) An effect size of 0.2 suggests 55% versus 45%

3. Effect Sizes for Selected Medical Interventions Mean Intervention Outcome effect size Bypass graft surgeryangina0.80 ECT depression0.80 AZT for AIDSmortality0.47 Drug treatment for hyperactivitybehavior0.47 to 0.96 Drug treatment for arthritispain, QoL0.45 to 0.77 Dipyridamoleangina0.24 Aortocoronary bypass surgery mortality0.15 Drug therapy for hypertensionquality of life0.11 to 0.28 Chemotherapy for breast cancermortality0.08 to 0.11

4. How Effective are Psychological & Behavioral Treatments? mean Intervention# studieseffect size General Psychotherapy 1231 0.79 Behaviour Modification 953 0.53 Family & Marital Counselling 295 0.55 Treating Juvenile Delinquents 871 0.29 Meditation & Relaxation 289 0.54 Biofeedback & Relaxation 109 0.65 Smoking Cessation 125 0.55 Psychological Treatment for Pain 219 0.90 Source: Lipsey MW, Wilson DB. The efficacy of psychological, educational, and behavioral treatment. American Psychologist 1993;48:1181-1209.