Mean, Median, Mode

Mean: The "mean" is the "average" you're used to, where you add up all the numbers and then divide by the number of numbers. 

Median: The "median" is the "middle" value in the list of numbers. To find the median, your numbers have to be listed in numerical order from smallest to largest, so you may have to rewrite your list before you can find the median. 

Mode: The "mode" is the value that occurs most often. If no number in the list is repeated, then there is no mode for the list.

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Give one example of a practical use - where you would find it useful.

When the average income for a country is discussed, the median is most often used because it represents the middle of a group. Mean allows very high or very low numbers to sway the outcome but the median is an excellent measure of the center of a group of data.

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Is it Useful: Yes because you can use it for different measures of center in a numerical data set. They each try to summarize a dataset with a single number to represent a "typical" data point from the dataset. 

Who invented mean, median, mode.

Mean: Edmund Halley

The term is first found in the mid-1690s in the writings of Edmund Halley, and it has been used to summarize observations of a variable since the time of Galileo

Median: Antoine Augustin Cournot 

In 1843 was the first to use the term median for the value that divides a probability distribution into two equal halves.

Mode: Karl Pearson

Early use of the statistical concept of the mode was by English mathematician Karl Pearson in 1895 when he stated that “I have found it convenient to use the term mode for the abscissa corresponding to the ordinate of maximum frequency”.

When was it first used: The term is first found in the mid-1690s.

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