A note on dropout-time modeling under phase-wise variable stress fixed cohort setup with grouped data

In this note, we revisit the accumulated-stress model for student dropout proposed by Biswas et al. (Biswas, A., Chakraborty, S., and Nandi, A. (2025). "Modeling the time to dropout under phase-wise variable stress fixed cohort setup." Journal of Applied Statistics, 52(3), pp. 702–714.). We consider grouped data, where the exact dropout times are unknown, but the number of dropouts in different phases is observed. This changes the likelihood function and affects the estimation of model parameters. We apply a frequentist approach to parameter estimation, supported by a simulation study and an illustrative analysis of a student dropout dataset.