This rescaling removes sources of systematic uncertainty such as errors in the methane and air flowrates. Furthermore, it allows the new results to be quantitatively compared with a database that contains measured YSIs for hundreds of organic compounds . We typically use n-heptane and toluene as the endpoint species (e.g., ), but in this case that would have required a large extrapolation since the YSIs of TET and especially 1MN are much larger than toluene (TET ≈ 400 and 1MN ≈ 650 vs. toluene ≈ 170). Therefore, 1MN and MDC were chosen as upper and lower endpoints specific to this study that were guaranteed to bracket the diesel mixtures. The endpoint values (YSI1MN and YSIMDC) were set to 620.1 and 60.1. These values were calculated with a group contribution model (GCM) (see SI D). Predicted values were used instead of measured values because (1) the predicted values are close to the measured values (649.1 and 50.4), and (2) the GCM combines the results for hundreds of measurements and therefore provides better consistency with other species.