Notes on Study Session 3

• Don't forget that sample mean is still found by dividing by total number of observations but the variance/standard deviation is divided by n-1
• Semivariance and semideviations are covered in the CFAI books but not in Schweser
• You are asked to calculate semivariance, semideviations, kurtosis and skew in CFAI books but not in Schweser (although the principles and concepts of kurtosis and skew are covered by Schweser)
• Semivariance and semideviation are just calculating the variance and the st. deviation using only the data below the mean - otherwise it is exactly the same. You will still use the sample mean and the sample total number of observations but you only sum the squares of the observations below the mean
• don't forget to check whether to divide by n or n-1 i.e. pop or sample
• modal interval is the interval with the most number of observations in it
• Geometric mean always screws me up because i keep doing some approximation of the standard deviation formula:
  Geometric mean = (((1+R₁)(1+R₂)...(1+Rn))^1/n)-1