Ehh, not _that_ carefully. Real inflation is notoriously difficult to track, as you need to take into consideration things like decreases in manufacturing quality, ingredient substitutions, planned obsolescence, etc.
Ehh, they try pretty damn carefully. They absolutely do take into consideration things like changing quality and ingredients.
> Pricing information is then sent to our national office, where specialists who have detailed knowledge about the particular goods or services review the data. These specialists check the data for accuracy and consistency, and make any necessary corrections or adjustments. Adjustments can range from an adjustment for a change in the size or quantity of a packaged item, to more complex adjustments based upon statistical analysis of the value of an item's features or quality. Thus, commodity specialists strive to prevent changes in the quality of items from affecting the CPI's measurement of price change.
> Hedonic quality adjustment is one of the techniques the CPI uses to account for changing product quality within some CPI item samples. Hedonic quality adjustment refers to a method of adjusting prices whenever the characteristics of the products included in the CPI change due to innovation or the introduction of completely new products.
