I got negative variance?

Question

help please? what does it mean? im doing a report on two biochemistry practical procedures and im trying to compare between the two using t-test and i've got negative variance. there's not much variation for the first procedure and there's no variation for the second one..at least i should get 0 for variance right?

Answer 1

Variance is defined as the sum of the squares of the differences between the data and the mean, divided by the number of items.  By definition variance cannot be negative.  (The difference between 2 variances can be negative if the larger is subtracted from the smaller.)