Why do you think that response time declined if all other quality factors have remained the same?

Acme Janitor Service has always taken pride in the fact that it had one of the highest customer response times in the home cleaning service industry. However, as the products manufactured for this industry have become more complex, the company's customer response time has declined.
What will be an ideal response?

Answer: If quality production was one of the other control factors, and the products became more complex, it probably takes more time to inspect and verify the quality of the finished products. Therefore, to maintain the same level of quality, additional time had to be put into the product cycle.