6. LONGITUDINAL STUDY
                                       
 
TYPICAL MEDICAL STUDY/LONGITUDINAL STUDY
    Eight Rules

1. False Precision

2. Base Rate Fallacy

3. Correlation Not Causation

4. Single Variable

5. Substantial Differences

7. Different From Chance

8. Dose-Response 		 

  •   Divide volunteers into two groups

  •   Give group one the drug

  •   Give group two a placebo

  •   Double-blind

  •   After six months, switch the groups
    •    
    Disadvantage:   Everyone knows they will receive the drug eventually; everyone knows they will eventually receive the placebo.     		 
     
    BETTER DESIGN
     
        1.   DRUG ------->   1.   DRUG   Groups 1 and 2 keep the same dosage throughout the study (drug or placebo); groups 3 and 4 switch.

    People and their doctors do not know which group they are in.     		 
        2.   PLACEBO ------->   2.   PLACEBO
        3.   DRUG ------->   3.   PLACEBO
        4.   PLACEBO ------->   4.   DRUG
      TOP
     
    DOUBLE-BLIND NOT ALWAYS FEASIBLE
    "STUDY" MAY BE UNPLANNED
     

  •   Exercise

  •   Diet

  •   Second-hand smoke

  •   Exposure to pollutants


  •   Death Penalty

  •   War on Drugs

  •   Mandatory Sentences

  •   Sentencing Guidelines
    		•  
      TOP Next