Lecture 4
Everything you need to know about correlation for this module is covered in the lecture and tutorial. Make sure you review the lecture slides and recording in depth, and then apply your knowledge in R using the tutorial.
One of the best ways to get the hang of correlations is to look at lots of them! Here are some examples.
In this visualisation (full website here), you can add, delete, and move data points to see how they change the correlation. Try the following to see what happens:
Remember, there are no right or wrong answers to these tasks. The goal is simply to play with different data shapes and see how the correlation changes as you do so.
This game (full website here) will help you develop a âfeelâ for what different values of r actually mean. Play as long as you like - although fair warning, it can be addictive!
Finally, this visualisation (by Milan) illustrates how the correlation coefficient is related to lines of best fit. We will cover âlines of best fitâ, or linear models, later in this module.
If you are interested in understanding correlation better, and have some familiarity with the equation of a line, read on. If you donât, donât worry - we will come back to this later, and this information wonât be on the quiz.
In this visualisation, the yellow line represents the value of y predicted by x. Conversely, the purple line represents the value of x predicted by y. The angle \(\alpha\) is the angle between these two lines. What this visualisation illustrates is that the cosine of \(\alpha\) is equivalent to the value of r, which you can see by dragging the slider along the bottom.
If you donât remember your trigonometry very well, thatâs fine! The main thing to notice here is how r corresponds to the strength of the relationship between x and y.
As mentioned in the lecture, we will apply what weâve learned about correlation in the practicals to investigate how mental health in young people is related to social media use. If youâre interested in this topic, you can read a bit around it ahead of your practical session; there are some resources below to get you started. However, you donât need to do this in order to participate in the practical.
NPR: A Rise In Depression Among Teens And Young Adults Could Be Linked To Social Media Use
APA Report: Stress in America - Generation Z
Meet the Millennium Cohort whose data we will be using in the practical
Give us feedback, ideas, or suggestions in the Suggestion Box
Recognise people who have helped you or others by nominating them for a SavioR award
Participate (optionally) in our statistics and growth mindset study!