From the course: Machine Learning Foundations: Statistics

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The covariance

The covariance

- [Instructor] Let's explore an interesting statistical measure that will help us understand the relationship between two data samples. Imagine a small fashion shop in Lisbon, Portugal and its owner would like to find out why some months, umbrella sales are skyrocketing and some months, they're struggling to sell a few of them. What do you think is the key factor that drives the sales? You probably got it right. It's the number of rainy days. Usually on rainy days, people come in to buy an umbrella as they need one. Let's look at the data table. The fashion shop in Lisbon keeps track on how many umbrellas they sell in a month versus the number of rainy days. Covariance is the measure of the relationship between two random variables. It can be positive, negative, or zero. The positive covariance tells us the values tend to rise together. The negative covariance tells us that one value rises as the other value falls.…

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