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Summary Statistics LN2 (2.1 Sample Average (Concept (Relative height of…

- - - - Probability values of phenomena will occur
  - - - Center
        
        underlying average
      - Width or spread
        
        underlying range
  - - - Average of samples
        
        Sample
        
        Collection of observations
        
        Not just one observation
        
        Drawn from same underlying distributions
        
        Samples averages can differ for same population
      - Chief Summary statistics
    - - Directly under curve peak
      - Population
        
        Population/Underlying/True average
        
        Only one grand average
        
        Symbol
        
        Mule
        
        Never really get a numeric value(too large or costly)
      - Sample
        
        Sample average
        
        Many possible sample averages
        
        Symbol
        
        X bar
- - - - Compute sample var.
      - Square root sample var.
        
        Why take the square root of the sample var.?
  - - - Each member of sample - sample average
        
        Why subtract sample average from each observations?
        
        To measure the scatter/spread of the sample relative to the center of the sample
      - Square each difference
        
        Why square the deviations?
      - Sum each squared difference
        
        Why do we take sum of the deviations?
      - Divide by (n-1)
        
        Why divide by number of observations?
        
        Why subtract 1 from number of observations?