The mean, median, and mode are single numbers that help describe how the individual scores
in a data set are distributed in value. A data set consists of the observations
for some variable is referred to as raw data or ungrouped data.
The Mean
The arithmetic mean is another name for the average of a set of scores. The
mean can be found by dividing the sum of the scores by the number of scores.
For example, the mean of 5, 8, 2, and 1 can be found by first adding up the
numbers. 5 + 8 + 2 + 1 = 16. The mean is then found by taking this sum
and dividing it by the number of scores. Our data set 5, 8, 2, and 1 has
4 different numbers, hence the mean is 16 ÷ 4 = 4.
The Median
The median of a set of data values is the middle value once the data
set has been arranged in order of its values. To find the mean of 2, 9, and 1,
first arrange in order: 1, 2, 9. The median is the middle number or 2.
If you have an even number of values such as 1, 2, 5, and 8, the median is
the average of the two middle numbers. The median for 1, 2, 6, and 8 is
the average of 2 and 6 = 4.
The Mode
The mode of a set of data values is the number in the set that appears most
frequently. For example, the number 5 appears three times in 1, 2, 5, 5,
5, 8, 8, 9. Since the number 5 appears the most times, it is the mode.
A set of numbers that can have more than one mode, as long as the number
appears more than once. In the data set 1, 2, 2, 3, 3, 4, 5. The mode
is 2 and 3. We also can say that this data set is bimodal.
If no number appears more than once, then the data set has no mode.
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