Answer:
Consumer Price index:
Consumer Price Index is important because it provides governments, individuals, and businesses with ideas concerning making informed decisions in a business environment. Further, the government uses the Complex Price Index to gauge product prices to determine whether an economy is going through stagflation, inflation, or deflation.
CPI does a horrendous job predicting inflation, it's government propaganda that fudges real inflation. We've been inflating money supply without mercy since Nixon took us off gold standard. USD has lost 98% of its value vs gold since then, that's why an ounce of gold costs 2k an ounce use to be $35.00 only 50 years ago. Printing $ not reflected in CPI, this is why we have a wealth gap and everything is so expensive. Government not being honest, CPI doesn't capture this.
If you select 20 normal grocery goods purchased 10 or 20 years ago either example works fine. Then purchase those same goods 10 or 20 years later, the CPI will say that basket of goods went up 27% but in real dollars spent they actually went up 65%.
Government has an interest to report inflation is low so they can print more money. This is why we came off gold standard, money needed to be backed by gold so it had real value, government didn't like this, that's why gold expensive, it's because dollar got weaker, gold last 3000 years hasn't changed , fiat money always goes away gets debased then new currency comes. Throughout history this is the case but gold goes nowhere