VRA ® GeoMonitor Monthly Update
Subscriber John Doe 
Subscription January 1, 2002-December 31, 2002
Update for December 2002
Country(ies) Monitored Pakistan
  

Glossary - Z-score
A Z-score is a measure of the distance from the mean of a distribution normalized by the standard deviation of the distribution. Mathematically: Z-score = (value-mean)/standard deviation. Z-scores are useful for quantifying how different from normal a recorded value is. Z-scores are particularly useful when combining or comparing different features or measures.

A Z score of 0 represents the mean of counts for all periods. Assuming a normal distribution, Z scores of -1, -2, -3 and +1, +2, +3 indicate that about 67%, 95% and 99%, respectively, of all values are expected by change to fall within this count. In short, higher (in absolute value) Z scores are likely to be more statistically significant in their deviation from the mean.

© 2003 by Virtual Research Associates