They track each item and weight them. The point isn't to track each item, the point is to track the general costs of consumer goods over time. Over time, what they track and how they weight them changes. So no, the point of the CPI isn't to track the price of a specific item.
I fully understand you feel like beans are lower quality, but that doesn't matter because it is not possible to track what you might have bought, so we track what you did buy. You may buy beans because bean companies go viral with their marketing, or because your local store is out of potatoes, or because you found a really good looking chili recipe you want to try. CPI doesn't try to explain why you bought beans, or didn't buy potatoes.
> So no, the point of the CPI isn't to track the price of a specific item.
Strawman. No one ever claimed that.
I'm not sure why you're continuing to argue here.
> but that doesn't matter because it is not possible to track what you might have bought
I can think of several ways of improving on the current system, two of which can be easily derived if you understand my previous post.
Spoiler: track the inflation of goods weighted by quantities purchased 1-2 years prior. And incorporate savings as a significant category such that the category CPI_savings = -(net_savings_this_month - net_savings_X_months_ago) / ((income_this_month + income_X_months_ago)/2). Still imperfect if most of the people answering the survey have no savings, but at least it would have captured the undocumented inflation from the 1980s-2010s that was hidden by decreasing savings.
I never claimed you can't improve CPI, or that it's even an accurate way to view changes in prices over time. My original comment was that when you choose to buy beans over another food, you are expressly showing you prefer to buy beans.
I fully understand you feel like beans are lower quality, but that doesn't matter because it is not possible to track what you might have bought, so we track what you did buy. You may buy beans because bean companies go viral with their marketing, or because your local store is out of potatoes, or because you found a really good looking chili recipe you want to try. CPI doesn't try to explain why you bought beans, or didn't buy potatoes.