With penalties and minimum withdrawal requirements to consider, timing is of the utmost importance when taking money from your IRA. (Getty Images) Individual retirement accounts, commonly known as IRAs, are retirement fund staples for many people.
In statistics, the mean is the mathematical average of a set of numbers. The average is calculated by adding up two or more scores and dividing the total by the number of scores. Consider the following number set: 2, 4, 6, 9, 12. The average is calculated in the following manner: 2 + 4 + 6 + 9 + 12 = 33 / 5 = 6.6.
Z-Scores; Empirical Rule. Suppose x is a value, or âscoreâ. We want to compare x to a data set (or population) with mean (or Î¼) and standard deviation s (or Ï). x may or may not be a part of the data set. Define the z-score for x as or. â¢ The z-score tells us how many standard deviations x is from the. mean. â¢ The further z is from zero, the more âatypicalâ x is, relative to. the given data set. In fact, the âempirical ruleâ states that for.