# How to calculate Z-score?

Does Z-score equal to (x-μ)/σ **(Section 3 video 4)** or equal to (x-μ)/standard error? **what formula do we use to standardize variable?**

**and** why do we use standard error when we have the population standard deviation?

what is the difference between these four terms **Z Test/z-score/z-statistic/critical value?**

1 answers ( 0 marked as helpful)

We are dealing with the sample data thats why we are using the standard error for standardization , we cannot use the standard deviation of population because in the formula we have same mean which x-bar.