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Statistical Inference (Definitions (Statistic - No describing…

- - - - Use t distribution with n-1 degrees of freedom (to estimate population distribution using sample distribution
        
        Confidence Interval
        
        Hypothesis test (3)
        
        Then find on t table - will get a range
        X 2 is 2 sided test
        
        If P less than sig lvl, we reject H not.
        
        Only used for continuous variables
      - Comparing 2 means HT (5) or CI (4), taking dof of smaller sample -1
        
        Can also estimate the probability that one mean is
        greater than another mean by x units
- - - - The sampling distribution of a
        sample proportion, p, is approximately Normal
        when sample size is large
      - mean = p
      - SD
      - If we take millions of samples - np will be successes
      - Large if both successes > 10, Failures > 10
      - For hypothesis test
        
        large if (equal to or greater) n(1-po)>10, npo>10
        
        Take -ve of z to get P
      - Comparing two large proportions
        
        (p1 est - p2 est) +-
        
        (6)
      - Test of Significance
        
        If successes and and failures > 5, large sample
        formula (7)
      - If sample small - some corrections you can make (e.g. approximating to the hypergeometric distribution).
  - - - Expected Count = r x c / n
      - Chi Sq statistic (8)
      - Dof = (r-1)(c-1)
      - No need to multiply by 2
      - Tells us if 2 categorical variables are associated
      - Larger X2 -> smaller the p-value —> association is more likely
- - - - As in the true mean is within this range