Math and Arithmetic

Why does a cumulative frequency graph never go down?

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Wiki User
November 21, 2010 3:39PM

Because of the word "cumulative". What that means is that the height of the graph for any value (X=x) is the number (or proportion) of observations that were less than or equal to the value x.

Now consider the cumulative value of the graph for a value of X which is bigger than x. All the previous observations were ≤ x and so they will be ≤ the newer, larger value. So the height of the cumulative graph cannot decrease. It may increase if there are any observations whose value was between x and the new value.