Recall in the course we learnt how to display data of two categorical variables by means of a contingency table. In this question, we will formulate a measure to quantify the level of association between the two categorical variables. Such a measure is often used in a statistical test called Chi-square test for assessing whether there is an association between two categorical variables. This question is also used to motivate the learning of independence and to connect the concept back to what we have learnt in the course.

How is diet type (high cholesterol diet versus low cholesterol diet) related to the risk of coronary heart disease? Data of 23 individuals:

\f