26. Video: Notation for the Mean

Final Steps for Calculating the Mean

To finalize our calculation of the mean, we introduce n as the total number of values in our dataset. We can use this notation both at the top of our summation, as well as for the value that we divide by when calculating the mean.

\frac{1}{n}\sum\limits_{i=1}^nx_i

Instead of writing out all of the above, we commonly write \bar{x} to represent the mean of a dataset. Although, similar to the first video, we could use any variable. Therefore, we might also write \bar{y}, or any other letter.

We also could index using any other letter, not just i. We could just as easily use j, k, or m to index each of our data values. The quizzes on the next concept will help reinforce this idea.

Notice

At second 0:12, this should say \sum\limits_{i=1}^5 x_i = x_1 + x_2 + x_3 + x_4 + x_5. The x_i is missing here in front of the summation.