Spread of data

• What is the advantage of using the IQR?

  Ignores outliars
• What is the formula for variance in listed data?

  Sums of the squares divided by the number of items minus the square of the mean
• What is the variance formula for grouped data?

  $(Σfx^2/Σf) - x̄^2$
• What is the variance formula for listed data?

  $(Σx^2/n)-x̄^2$
• What is the saying for finding the variance?

  "mean of the squares minus the square of the mean"
• How do you calculate the standard deviation of data?

  Square root of the variance