Outline
      •  Statistical inference
      •  Hypothesis testing
      •  Type I and type II errors
      •  Student t test
      •  ANOVA
      •  Parametric vs non-parametric tests
         Importance of biostatistics
     •
       Diabetes type 2 study
         – Experimental group:  Mean blood sugar level: 103 mg/dl
         – Control group:   Mean blood sugar level: 107 mg/dl
     •
       Pancreatic cancer study
         – Experimental group:  1-year survival rate: 23%
         – Control group:   1-year survival rate: 20%
          Is there a difference?
     Statistics are needed to quantify differences that are too 
       small to recognize through clinical experience alone.
               Statistical inference
    •
      Diabetes type 2 study
    •
      Experimental group:   Mean blood sugar level: 103 mg/dl
    •
      Control group:    Mean blood sugar level: 107 mg/dl
    •
      Increased sample size:
    •
      Diabetes type 2 study
    •
      Experimental group:   Mean blood sugar level: 99 mg/dl
    •
      Control group:    Mean blood sugar level: 112 mg/dl
                 Statistical inference
                µ                             µ
                 1   X1                X2      2
     •  Compare the mean between 2 samples/ conditions
     •  if 2 means are statistically different, then the samples 
        are likely to be drawn from 2 different populations, ie 
        they really are different  
               Statistical inference
    •
      Diabetes type 2 study
    •
      Experimental group:   Mean blood sugar level: 103 mg/dl
    •
      Control group:    Mean blood sugar level: 107 mg/dl
    •
      Increased sample size:
    •
      Diabetes type 2 study
    •
      Experimental group:   Mean blood sugar level: 105 mg/dl
    •
      Control group:    Mean blood sugar level: 106 mg/dl