VarScoreStat:
Compute the estimate of the covariance of the test statistic in the score test
Description
The function computes the estimate of the covariance of the test statistic of the score test proposed by Finkelstein (1986).
References
Finkelstein, DM (1986), "A Proportional Hazards Model for Interval-censored Failure Time Data", Biometrics, 42: 845-854.