Your investigation determines that in August he treated 7 type X patients with an average cost of $4,300 and 11 type Y patients with an average cost of $9,000. In September, he treated 8 type X patients and 10 type Y patients. Costs in September for his patients were $5,000 for type X and $8,700 for type Y. Although the August cost for type X patients had risen, Eger points out that costs for the higher-volume, higher-cost type Y patients had fallen. Develop a case-mix variance and a cost variance so we can better understand the impact on HOS of the changes in Dr. Eger’s practice from August to September. What other information would be of interest in this particular case?