Tuesday, 28 June 2016

Mean, Median, Mode

Finding Central value




 

The Mean

So far we have been calculating the Mean (or the Average):



FORMULA:
Mean: Add up the numbers and divide by how many numbers.
 




The Median

But you could also use the Median: simply list all numbers in order and choose the middle one.


Sometimes there are two middle numbers. Just average them:



The Mode

The Mode is the value that occurs most often.




Well, Middle Number it is!

But Mode can be tricky, there can sometimes be more than one Mode.


Now, Let's take a look at this video. hope it helps!




Outliers

Outliers are values that "lie outside" the other values.



They can change the mean a lot, so we can either not use them (and say so) or use the median or mode instead. 





The Range

The Range is the difference between the lowest and highest values.

Example: In {4, 6, 9, 3, 7} the lowest value is 3, and the highest is 9.
 
So the range is 9-3 = 6.


 SIMPLE!

But.....................
The Range can be misleading
when there are extremely high or low values.


Example:
 {8, 11, 5, 9, 7, 6, 3616}


the lowest is 5
the highest is 3616 
So the range is 3616-5 = 3611.

The single value of 3616 makes the range large, but most values are around 10.


Now, Let's try some exercises!

References:

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