In an increasingly data-driven world, it is more important than ever for students as well as professionals to better understand basic statistical concepts. 100 Questions (and Answers) About Statistics addresses the essential questions that students ask about statistics in a concise and accessible way. It is perfect for instructors, students, and practitioners as a supplement to more comprehensive materials, or as a desk reference with quick answers to the most frequently asked questions.

# Why Is the Unbiased Estimate of n – 1 Used, Rather Than Just the Biased n, in the Computation of the Standard Deviation and the Variance?

### Why Is the Unbiased Estimate of n – 1 Used, Rather Than Just the Biased n, in the Computation of the Standard Deviation and the Variance?

You’ll remember from our discussion of the computation of the standard deviation, in question #21, that the standard deviation is the average distance of each score from some central point in a set of scores. And, you’ll remember that this “average” is computed by dividing the total distance by the number of observations.

But, in this case, instead of using n to represent the size of the sample, we use n – 1. Why?

A general idea that drives the use of statistics is that it produces values and results that can be trusted, in the sense that statistical outcomes ...