The burst time is needed for Shortest Job First (SJF) and Shortest Run Time First (SRTF) scheduling. To get the approximate burst time, we use the equation $$\tau_{n + 1} = t_n + (1 - \alpha)\tau_n$$
I want to ask whether $\tau_{n + 1}$ is the predicted burst time of the $n + 1$ th process or it is the predicted burst time of some process say p which is demanding the CPU for the $n + 1$ th time.