Example 1.5 studied a variant of the gene ACTN3 which inhibits fast-twitch muscles and seems to be less prevalent in sprinters. A separate study indicated ethnic differences: Approximately 20% of a sample of Caucasians, approximately 25% of a sample of Asians, and approximately 1% of a sample of Africans had the gene variant. What are the variables in this study? Classify each as categorical or quantitative.