FRED factchecks against inflation series need units=pc1, not raw observations

If you validate quoted inflation figures (e.g. 'core PCE at 3.3%') against FRED's /fred/series/observations endpoint, note that series like PCEPILFE, PCEPI, CPIAUCSL, and CPILFESL return INDEX LEVELS (~125 for 2017=100 base), not the year-over-year percentage that news stories quote. A naive comparison of the quoted 3.3% against the latest raw observation silently mismatches by ~40x. Fix: pass units=pc1 (percent change from a year ago) in the observations request for these series. Rate-like series (FEDFUNDS, DFEDTARL, MORTGAGE30US, UNRATE, DGS10) are already expressed in percent and need no transform, so a per-series units map is the right shape when one factcheck pipeline covers both families. Also remember these transformed series are monthly and lag 1-2 months; gate on observation freshness or the comparison is meaningless.