of the Jakarta MRT on ride-hailing activity in the vicinity of our, still-to-be-opened, Phase 2A station control locations relative to the intermediate Phase 1 control locations. Second, we apply a “ring-based” method to our control locations only and find no differential impact of the opening of the MRT on locations closest to these control locations.

In our event study design, we take 12 March 2019, i.e., the date on which the limited public trial period of the Jakarta MRT commenced (see Section 2 above), as our baseline event date for which we set _k = 0_ . Next, we estimate the effect of the opening of the MRT for each daily time window, _k = {-90, -89 ,..., +89,_ + _90}_ up to 90 days before and after 12 March 2019: up to 90 days before and after 12 March 2019: 90 ∙ [1] i = ∑ i kk kk=−90 kk ii ii ii ii where i is the log number of ride-hailing trips originating and terminating at location yy ββ DD ∙TT + αα + γγ + εε _i_ (i.e., the sum of drop-offs and pick-ups at location _i_ ) on date _t_ . is a dummy variable that equals one if date _t_ lies _k_ days yy kk from 12 March 2019, and zero otherwise, and ii is a dummy variable that equals one if location _i_ is a DD treatment location (i.e. a station location on the Phase 1 line) and zero otherwise. ii and are location and TT date-specific fixed effects respectively. The location fixed effects control for time-invariant location ii ii αα γγ characteristics, such as fixed neighborhood amenities, which may be correlated with both ride-hailing activity and treatment status. The date-specific fixed effects control for contemporaneous shocks that are common across all locations. This includes, for example, whether the date falls on a weekend or is a public holiday, as well as weather-related shocks that may affect ride-hailing activity. i is the error term. Our main parameters of interest are the ’s. They tell us whether, and if so how, for each day in our sample εε period separately, ride hailing activity near the newly opened MRT stations relative to that in the control kk ββ locations differs from that on 12 March 2019, the day on which the limited public trial of the Jakarta MRT = commenced. Prior to 12 March 2019, we therefore expect 0. In fact, our ability to estimate treatment effects prior to the opening of the MRT allows us to assess the crucial assumption underlying our estimates kk ββ that ride-hailing activity did not show differential trends in treated and control locations before the MRT was opened. In the period after the opening of the MRT, we expect > 0 if the MRT and ride-hailing are complements and < 0 if they are substitutes. Furthermore, our daily estimates also allow us to look for kk ββ patterns in the estimated kk coefficients that would, for example, be consistent with people gradually ββ adjusting their behavior following the opening of the MRT, or to look for differences in the effect between kk ββ the limited public trial period, the fully operational, but continued fare free, period between 24 March 2019 and 1 April 2019, the period between 1 April 2019 and 13 May 2019 during which fares where charged at a 50 percent discount, and following the introduction of full fares on 13 May 2019. We estimate equation [1] clustering standard errors by location.

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