The evolution of consumer prices is not uniform across categories, and there can be stark differences between relatively similar products. In the example above, we look at two types of books: those used for recreation and those used for education. The paths of their price indices are very different, even in the long term. While this example is rather extreme, there are plenty of others in the disaggregated CPI data. This shows that one should not use personal experience with the price of a very specific product to draw conclusions about the general price level.
How this graph was created: Search for “CPI book.” To weed out the price indices from other countries, click on USA in the left sidebar tags. Select the two series, not seasonally adjusted (as one is not available seasonally adjusted). Finally, select a right axis for one series, as they have different index years.
Suggested by Christian Zimmermann