Test Yourself
True or False
Indicate whether the following statements about scatter plots are true or false.
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False
We could also plot means or summary statistics from a group of observations, for example the average income from different countries.
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False
Scatter plots are used for visualising the relationship between two numerical variables
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True
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True
They are very useful for checking for the consistency between observations and identifying suspicious observations.
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False
It takes values from -1 to +1, negative numbers indicate a negative relationship and positive numbers a positive relationship.
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False
It is important to realise that it only measures the strength of LINEAR association between two continuous variables. If a relationship not linear then a correlation coefficient can be misleading.
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False
The correlation coefficient is a dimensionless measure, it tells us nothing about the steepness of slope of a relationship in real units ie, how much Y will increase if we increase X by one unit. It only tells us about the degree of scatter around a linear line.