Recall & Review
beginner
What is correlation analysis?
Correlation analysis measures the strength and direction of a relationship between two numeric variables.
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beginner
Which R function is commonly used to calculate correlation?
The
cor() function calculates the correlation coefficient between two numeric vectors or columns.Click to reveal answer
beginner
What does a correlation coefficient of 0 indicate?
It indicates no linear relationship between the two variables.
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intermediate
How do you interpret a correlation coefficient of -0.8?
It shows a strong negative linear relationship: as one variable increases, the other tends to decrease.
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intermediate
What are the common methods for correlation in R's cor() function?
The methods are
"pearson" (default), "spearman", and "kendall".Click to reveal answer
Which R function calculates the correlation coefficient?
✗ Incorrect
The
cor() function computes correlation coefficients between numeric vectors.What does a Pearson correlation coefficient of 1 mean?
✗ Incorrect
A value of 1 means the variables increase together perfectly in a straight line.
Which correlation method is non-parametric and based on ranks?
✗ Incorrect
Spearman correlation uses ranks and does not assume normal distribution.
If cor(x, y) = -0.5, what does this indicate?
✗ Incorrect
A value of -0.5 shows a moderate negative linear relationship.
Which argument in cor() specifies the correlation method?
✗ Incorrect
The
method argument sets the correlation type: "pearson", "spearman", or "kendall".Explain what correlation analysis is and how you perform it in R.
Think about measuring relationships between two numbers.
You got /3 concepts.
Describe the difference between Pearson and Spearman correlation methods.
One uses actual values, the other uses order.
You got /3 concepts.