when scientists or statisticians talk about the modal observation they are referring to the most common observation 
mode vs mean vs medianmean median and mode are all different ways of noting the center of a data set mode is the most common set of numbers while mean is the average and median is the midpoint the mean is the average of a set of numbers to calculate the mean begin by adding up all of the data points and dividing by the total number of data points for example suppose you have the following series of numbers added together you get 208 divide 208 by 11 the number of data points to get the mean which is 18 9 the median is the data point in the middle of a set to find the median the numbers in the set must be arranged from smallest to largest let s use the numbers in the example above the median is 16 the data point in the exact middle of the set this set has an odd number of data points which makes it easier to find the middle for a set with an even number of data points you d take the mean of the two middle numbers to find the median advantages and disadvantages of the modethe mode is easy to understand and calculate the mode is not affected by extreme values the mode is easy to identify in a data set and in a discrete frequency distribution the mode is useful for qualitative data the mode can be computed in an open ended frequency table the mode can be located graphically 