Click to draw/clear town borders. Notable locations in Westfield: Westfield Station (A), Echo Lake Golf Course (B), Westfield Volunteer Rescue Squad (C), Union County Fire Science Training Academy (D), Westfield Fire Department Station 2 (E), Westfield Rescue Squad (F), Westfield Fire Department Station 1 (G).
A distribution is said to be symmetric if the relative frequency (or probability) is the same the same distance either side of its centre, m. Mathematically, the distribution of X-m is then the same as the distribution of m-X.The mean and median of a symmetric distribution are equal.The most important symmetric distribution is the normal distribution, which is unimodal and therefore is symmetric about the mode.athematically, the distribution of X-m is then the same as the distribution of m-X. The mean and median of a symmetric distribution are equal. The most important symmetric distribution is the normal distribution, which is unimodal and therefore is symmetric about the mode.
Since half the values in a distribution lie between Q 3 and Q 1, the semi-quartile range is one-half the distance needed to cover half the values. In a symmetric distribution, an interval stretching from one semi-quartile range below the median to one semi-quartile above the median will contain one-half of the values.uartiles. The median divides the data into two equal sets. For more information on the median, refer to the chapter on Measures of central tendency 1  : The lower quartile is the value of the middle of the first set, where 25% of the values are smaller than Q 1 and 75% are larger.