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Estimating Correlation

Practise the skill of estimating the correlation of data on a scatter graph in this self marking exercise.

Level 1 Level 2 Real Life Exam-Style Description Help More Statistics

This is level 1: Estimating the type of correlation in words. You will be awarded a trophy if you get at least 9 correct and you do this activity online.

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This is Estimating Correlation level 1. You can also try:
Level 2 Real Life

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Description of Levels



Level 1 - Estimating the type of correlation in words

Level 2 - Estimating Pearson's Correlation Coefficient

Real Life - Arrange the given statements in groups to show the type of correlation they have.

Exam Style Questions - A collection of problems in the style of GCSE or IB/A-level exam paper questions (worked solutions are available for Transum subscribers).

More on this topic including lesson Starters, visual aids, investigations and self-marking exercises.

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Curriculum Reference

See the National Curriculum page for links to related online activities and resources.


The video above is from the excellent Corbett Maths.

Phrases like "strong", "moderate" or "weak" are used to describe the strength of the correlation, and it's usually subjective, there is no definitive agreement on how to match the phrases to the Pearson Product-Moment Correlation Coefficient

The thresholds for labelling a correlation as "very weak", "weak", "moderate", "strong", or "very strong" are somewhat arbitrary and can vary depending on the field of study or the preferences of a researcher.

For instance, in some social sciences, correlations are often lower, so a researcher might consider a correlation of 0.4 as "strong". In contrast, in some natural sciences where relationships might be more deterministic, a "strong" correlation might require a higher threshold.

Here's one of the common scales:

However, others might use a different scale like:

It's also important to remember that Pearson's r only measures linear relationships. Therefore, even if Pearson's r is close to 0, there might still be a strong non-linear relationship between the variables.

In practice, it's often good to not just rely on the value of Pearson's r, but also visually inspect the data through scatter plots and consider the context of the data being analysed. The terminology one uses to describe the strength of a correlation should be carefully chosen based on the standards of the field and the nature of the data.

In order to complete this exercise, because there are nine different examples, you could order the diagrams then order the phrases or coefficients in order to make a ranking match.

Don't wait until you have finished the exercise before you click on the 'Check' button. Click it often as you work through the questions to see if you are answering them correctly. You can double-click the 'Check' button to make it float at the bottom of your screen.

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