Like most things, there are trade-offs involved. Including X & Y may greatly skew the results higher or lower, but if the percentage of people purchasing X & Y

Like most things, there are trade-offs involved. Including X & Y may greatly skew the results higher or lower, but if the percentage of people purchasing X & Y are low, then they don't have much impact. The CPI methodology isn't great, but it also isn't bad. Removing volatile sectors makes sense when trying to identify trends, but it doesn't make sense when those volatile sectors are a large component of consumer spend. Since most of the data used by the CPI calculator is publicly available, it is possible for people to construct their own CPI metric and track it over time. This is helpful if you want to get an accurate indicator of the inflation you've experienced over time, or if you're wanting to push the narrative of higher/lower inflation over a period of time.