empirical rule

empirical rule

Approximately 68 percent of the scores in a normal distribution are within one standard deviation, plus or minus, of the mean; approximately 95 percent of the scores are within two standard deviations; and approximately 99.7 percent of scores are within three standard deviations of the mean.
    • Related Articles

    • z distribution

      Z distribution is also called normal distribution or bell-shaped distribution; unimodal, symmetrical, most scores clumped in the center, few scores far away from center; this is a frequently used probability distribution; the shape of the z ...
    • normal distribution

      Normal distribution is unimodal, symmetrical, mostly scores clumped in the center, few scores far away from center; also known as bell-shaped distribution; this is a frequently used probability distribution; the shape of the normal distribution ...
    • random assignment

      Random assignment is a method of assigning subjects to one experimental condition or another; it helps us rule out confounding variables by ensuring that any variables that affect our outcome variable, whether positively or negatively, will balance ...