16.3.2. Formula

Try these first

1. 1.

   What is the formula for covariance?

   Hint

   Consider the expected value and average deviations.

2. 2.

   What does a positive covariance indicate?

   Hint

   Think about how two variables relate to each other.

3. 3.

   What is the possible range of covariance?

   • -1 to 1
   • 0 to 1
   • -∞ to ∞

   Hint

   Consider how variables can differ broadly.

4. 4.

   True or False: A correlation of 1 indicates a perfect negative correlation.

   • True
   • False

   Hint

   Think about the direction of the relationship.

5. 5.

   A dataset represents heights (in cm) of individuals: {150, 160, 170, 180}. Another dataset gives weights (in kg): {50, 60, 70, 80}. Calculate the covariance and correlation.

   Hint

   Start by finding the averages and then apply the formulas.

6. 6.

   Discuss how correlation can be misleading in determining relationships, using an example from public health.

   Hint

   Consider third variables that could influence the correlation.