題組內容

第一大題

Let X be a nominal categorical random variable taking values in {0,1,2}. Let Y and Z be continuous random variables both taking values in [0,∞). Suppose you randomly select 100 samples from the population.

4. (5%) Figure I-B shows the scatter plot of the sample observations of X and Y. The sample correlation of the two variables is -0.75. Do you think it is appropriate to use this measure to quantify the relationship between variables X and Y? Explain your reason.