Final answer:
The option that is not a widely acknowledged problem with using the CPI is the 'unmeasured price change' since the CPI's primary purpose is to measure price changes, despite some imperfections in accurately capturing quality improvements or new product inclusions.
Step-by-step explanation:
The question is which of the listed options is not a widely acknowledged problem with using the Consumer Price Index (CPI) as a measure of the cost of living. The known issues with the CPI include substitution bias, which occurs because the CPI does not fully account for consumers substituting goods whose prices rise significantly with less expensive alternatives. There's also the challenge of introducing new goods and the related price changes that the CPI might miss if these goods aren't included in the index until after their prices have stabilized. Another problem is the unmeasured quality change, where improvements in product quality are not always accurately reflected in the CPI. These quality changes can include enhancements to products like computers in terms of speed, memory, screen size, and other factors. However, unmeasured price change is not commonly cited as an issue since the CPI does in fact measure price changes, although it may not always measure them perfectly.