Sample Statistics

# The Sample Covariance

## The Problem

The sample covariance is an non-standardized measure of the relationship between two numeric variables. It is used to summarize the bivariate relationship. To illustrate the calculations, let us use the following example.

A professor would like to investigate the relationship between student score on the midterm and the final exam. To do this, the professor collected the exam scores from n = 5 students. Using the data below, what is that covariance?

Here is the data. Note that there are two measurements on each unit (student). We are interested in the relationship between those two measurements.

Table of the bivariate data generated
StudentMidtermFinal
IdentifierScoreScore
15074
26499
31612
4316
57337

Calculate the covariance of this sample.