It is often unnecessary to present the experimental data in their entirety, either in tabular or graphical form. In such cases, the data and distribution can be represented by various parameters. One type of parameter is a measure of central tendency, Mode, median, and mean are measures of central tendency.
The mode is the observed value that occurs most frequently. The mode may vary greatly between series of observations. Therefore, its main use is a quick measure of the central value since little or no computation is required to find it. Beyond this, the usefulness of the mode is limited.
The median is the point in the distribution that partitions the total set of observations into two parts containing equal numbers of observations. It is not influenced by the extremity of scores on either side of the distribution. The median is found by counting up (from either end of the frequency distribution) until half of the observations have been accounted for.
Similar in concept tot he median are percentiles (percentile ranks) quartiles and deciles. The median could also have been called the 50th percentile observation. Similarly, the 50th percentile would be the observed value for which the cumulative frequency was 80%. The quartile and decile points on the distribution divide the observations or distribution into segments off 25% and 10%, respectively.
