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Test Yourself

True or False

Question 1

A log transformed variable contains units that represent an equal amount of multiplicative change in a variable.

Question 2

We often use a log transform to make a left hand skewed variable more normal.

Question 3

A geometric mean is equal to the arithmetic mean when data are positively skewed.

True or False

The mean of log BMI in a group of boys who play football is 2.8 and 2.9 for a group of boys that play rugby.
The back transformed difference of these two logged means is 1.11. State whether  the following interpretations are true or false:

 

Question 1

The difference in log BMI between footballers and rugby players in our sample was 0.1, meaning rugby players tended to have a higher BMI.

Question 2

Rugby players had a BMI that is about 1.11% higher than footballers in our sample.

Question 3

In our sample, on average rugby players are about 11% more likely to be heavier compared to footballers.

Question 4

Rugby players in our sample were 11% heavier on average compared to footballers.