Research Methods RE: Mean, Median and Mode

The mean, median and mode are all measures of central tendency.
Central Tendency- Descriptive statistics that identify which value is most typical for the data set

The Mean
Adding all of the scores in a data set together and dividing by the number of scores.
e.g. Height/cm; 153, 146, 151, 170, 160
Added together =780
780 divided by 5 =156cm
The mean =156

Advantages:

• The most powerful measure of central tendency because it it made up from all of the scores in the data set

Disadvantages:

• Any rogue outliers can distort the mean making it untypical of the data set
• Sometimes the mean does not make sense in terms of the data set e.g. the number of children per family in the UK = 2.4

The Median
When all of the scores in a data set have been put in order, the median is the central number in the set.
E.g. Age of employees/years; 21, 29, 34, 44, 56
The median age of the employees is 34

Advantages:

• The median is less effected by extreme scores than the mean

Disadvantages:

• It is not suited to being used with small sets of data especially if containing widely varying scores
  e.g. 7, 8, 9, 102, 121 where the median would be 9. A more real median would be 60!

The Mode
The most frequent occuring number in the data set when put in order
e.g. Days off work because of sickness; 3, 5, 6, 6, 6, 8, 9.
Mode = 6

The data set could be Bimodal (two modes) or even multimodal

Advantages:
The mode is normally unaffected by extreme scores and may give an idea of how often something is occurring e.g. what size of shoes sell most when ordering stock

Disadvantages:
The mode may not be central measure, and a set of data may not have a most frequent score