“…If the underlying truncation time is uniformly distributed, left truncation reduces to length‐biased sampling (Vardi, ), that is, the probability of selecting a subject is proportional to the length of his or her underlying failure time; see a comprehensive review by Shen et al (). Among the newly developed regression methods for length‐biased data, many show considerable improvement of efficiency in estimation compared with the conditional approach by incorporating information from the observed truncation times (Qin and Shen, ; Qin et al, ; Huang et al, ; Huang and Qin, ; Ning et al, ). Nevertheless, when the uniform truncation assumption is violated, these methods may yield inconsistent estimates (Huang and Qin, ).…”