Total is the sum of 
the measured quantity for the items.
 
Mean is the
Total divided by the number of items, also know as 
the average.
 
Median is the number 
in the middle when the data is arranged in increasing order.
 
Mode is the number 
that appears most frequently in the data.
 
Range is the 
difference between the largest number and the smallest number in the data.
 
Variance describes 
how far the data is from the mean or, in other words, how well the mean 
represents the data. The variance is calculated by first subtracting the value 
of each item from the mean and squaring each result individually. Then, all the 
squared terms are added together and the total is divided by one less than the 
total number of items (or squared terms).
 
Deviation is the 
average distance of each item from the line that best fits the data. This value 
is calculated by taking the square root of the Variance
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