why is z score so important 
a z score is important because it tells where your data lies in the data distribution for example if a z score is 1 5 it is 1 5 standard deviations away from the mean because 68 of your data lies within one standard deviation if it is normally distributed 1 5 might be considered too far from average for your comfort the bottom linea z score is a statistical measurement that tells you how far away from the mean or average your datum lies in a normally distributed sample at its most basic level investors and traders use quantitative analysis methods such as a z score to determine how a stock performs compared to other stocks or its own historical performance in more advanced z score uses traders weigh investments based on desirable criteria develop other indicators or even try to predict the outcome of a trading strategy 