FIGURE 2.

The survivorship curves based on real lifespan (blue lines) and reported lifespan (red lines). The simulated data were generated by Weibull distributions with shape parameters equal to 1.25 (a), 1.5 (b), 2 (c), and 3 (d). As the shape parameter increases, the convexity of the survivorship curve based on real lifespan (blue lines) is increasingly evident, while survivorship curves are almost straight, with a somewhat concavity, based on reported lifespans (red lines)