ABSTRACT
For example, if we know that a person has scored 70 on an IQ test that has a mean of 100 and a standard deviation of 15, then, using the equation for z, we can see how many standard deviations this is below the mean:
= −2
We can use a z-test to calculate the significance of the difference between a mean of a sample and the mean of a population, using the following equation:
In standard notation, this is usually shown as:
In this way we can calculate how likely a mean from a sample is to have come from a population with a given mean and SD.
