Please help explain the question

Question

What does Chebychev's inequality measure?

Answer 1

Chebyshev's inequality measures the percent of data that must lie within k standard deviations of the mean.  The value is 

 

100*[1 - (1/k²)]  

 

So for example, plugging in k = 2 says that at least 75% of the data must lie within 2 standard deviations of the mean.  

 

Note that Chebyshev's inequality is true for ANY data set, there is no requirement that the data come from a normal distribution.