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January 1st, 2016, 08:49 AM  #1 
Senior Member Joined: Oct 2013 From: Far far away Posts: 422 Thanks: 18  What can you say about the data?
Suppose that the variance for a set of data is zero. What can you say about the data? Variance depends on the squared difference of the individual values and the mean. Variance is zero if and only if the difference of the individual values and the mean is zero. In other words, all values in the data set must equal the mean e.g. the data set 4, 4, 4, 4, 4 has zero variance. Am I correct? Thanks. 
January 1st, 2016, 02:02 PM  #2 
Global Moderator Joined: May 2007 Posts: 6,436 Thanks: 562 
yes

January 1st, 2016, 02:14 PM  #3 
Math Team Joined: Jan 2015 From: Alabama Posts: 2,953 Thanks: 800 
Yes, the only way a sum of squares (of real numbers) can be 0 is if each number is 0.


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