Why jackknifing yields good latency estimates

We compared individual-participant and jackknife-based methods for scoring the onset latencies of event-related potential (ERP) components using a diffusion process as a model for an ERP. We studied "ramp-like" components in which the true ERP increases or decreases monotonically, except for noise. If the growth rates of such components vary across participants, the jackknife-based measure can easily have only 10%-20% as much error variance as the traditional method, and this advantage is magnified with more participants. We also studied intersection-shaped or "bump-like" components. Jackknifing generally yielded smaller error variances with these components too, especially when the component's peak amplitude varied across participants, but less so if the component's peak latency varied. These results help illuminate the reasons for the superiority of jackknife-based onset latency measures over traditional measures in recent simulations.