Seasonal adjustment. Like many government data series, the CPI is published in both unadjusted and seasonally adjusted forms. The BLS says that it “strongly recommends using indexes unadjusted for seasonal variation

(i.e., not seasonally adjusted indexes) for escalation.” “Escalation” here means adjusting wage or other payments to keep up with changes in the CPI. Why is the unadjusted CPI preferred for this purpose?