Add to difficulties in measuring inflation :
1. Selection of basket of goods
This is difficult to assess because the economy might be selecting a basket of goods that only reflect the expenditure of consumers in the past years and may not reflect current consumption. Furthermore, different households may place a different weightage on the goods leaving the inflation calculated to be unable to be applied to certain households.
2. Selection of base year
Every year, consumer tastes changes, population increases and the work force changes. This may lead to change in spending habits and therefore it might not even show that the economy is really undergoing inflation as compared to the base year. There may be just an increase in the standard of living.
Well, I'm not particularly 100% SURE on the above, but I think you can consider
Lemme know if there are mistakes.
