16 GOOLSBEEANDKLENOW 6. For each ELI we then computethepriceindexforELIj foragivenmonth byusingageometricaverageof“pricerelatives”:  w Y p i,j,t Π = i,j,t j,t p i∈j i,j,t−1 v +v p q wherew = i,j,t−1 i,j,t and v =Pi,j,t i,j,t . i,j,t 2 i,j,t p q i i,j,t i,j,t 7. WethenaggregatetheELIindicesusingmonthlycPIrelativeimportance weightstoarriveatourDigitalPriceIndex(DPI): Π = XW Π t j,t−1 j,t j wheretheW aretheCPIweightsforeachELI-month.9 j,t−1 8. We follow the BLS and do something special for apparel. Apparel prices exhibit a sawtooth pattern over seasonal and fashion cycles. We compute theaverageunitpriceforeveryclothingELI,ratherthancreateamatched- modelindexwhichwouldexhibitsharpdeflation. TableA1: RobustnesstoTrimming 2014 2015 2016 2017 Trim=0/Leveltrim=0 Headline -2.17 -1.58 -2.36 0.20 HeadlineexApparel -2.70 -0.82 -1.17 1.46 Trim=0/Leveltrim=0.01 9https://www.bls.gov/cpi/tables/relative-importance/home.htm