  One straightforward metric to evaluate a survival prediction model is based
on the Mean Absolute Error (MAE) -- the average of the absolute difference
between the time predicted by the model and the true event time, over all
subjects. Unfortunately, this is challenging because, in practice, the test set
includes (right) censored individuals, meaning we do not know when a censored
individual actually experienced the event. In this paper, we explore various
metrics to estimate MAE for survival datasets that include (many) censored
individuals. Moreover, we introduce a novel and effective approach for
generating realistic semi-synthetic survival datasets to facilitate the
evaluation of metrics. Our findings, based on the analysis of the
semi-synthetic datasets, reveal that our proposed metric (MAE using
pseudo-observations) is able to rank models accurately based on their
performance, and often closely matches the true MAE -- in particular, is better
than several alternative methods.
