In this week I learned what a z score is and why it is used. A z score shows how many standard deviations above or below the mean, a set of data is. This is especially useful in figuring out if your piece of data was in a higher percentage of people who passed a test, or if you were below the average and failed. The standard score is a very useful statistic because it (a) allows us to calculate the probability of a score occurring within our normal distribution and (b) enables us to compare two scores that are from different normal distributions.