Skip to contents

Find the dose cut in dose_grid that with true_dlt_rate falls in interval of prob_target_cut

Find_Dose_Cut.Rd

Find the dose cut in dose_grid that with true_dlt_rate falls in interval of prob_target_cut

Usage

Find_Dose_Cut(dose_grid, true_dlt_rate, prob_target_cut, return_idx = FALSE)

Arguments

dose_grid

numerical vector of doses

true_dlt_rate

numerical vector, the underlying DLT rate for each dose provided in dose_grid

prob_target_cut

a length-2 numeric vector of DLT rate cut. For the DLT rate:

  • [0, prob_target_cut[1]) is underdose interval;

  • [prob_target_cut[1], prob_target_cut[2]) is target dose interval;

  • [prob_target_cut[2], 1] is overdose interval.

Please refer to Details section about the difference and relationship between prob_target_cut and dose_target_cut

return_idx

boolean, whether to return the dose_target_idx (with return_idx = TRUE) or the dose_target_cut (with return_idx = FALSE).

Details

Difference and relationship between prob_target_cut and dose_target_cut

The prob_target_cut is for DLT rate, it divide the toxicity of a dose level into 3 categories:

  • The left-close, right-open interval [0, prob_target_cut[1]) is underdose interval;

  • The left-close, right-open interval [prob_target_cut[1], prob_target_cut[2]) is target dose interval;

  • The left-close, right-close interval [prob_target_cut[2], 1] is overdose interval.

While dose_target_cut stores the TWO cutting dose specified in dose_gird and these cutting dose satisfy the following properties:

  • For doses specified in dose_grid that fall in this left-close, right-close interval [0, dose_target_cut[1]], they are all under dose with corresponding DLT rate < prob_target_cut[1]

  • For doses specified in dose_grid that fall in this left-open, right-close interval (dose_target_cut[1], dose_target_cut[2]], they are all target dose with corresponding DLT rate >= prob_target_cut[1] and DLT rate < prob_target_cut[2]

  • For doses specified in dose_grid that fall in this left-open, right-open interval (dose_target_cut[2], Inf), they are all over dose with corresponding DLT rate >= prob_target_cut[2]

Note that even though prob_target_cut and dose_target_cut both utilize the under/target/over dose notion, the open/close settings of the parenthesis are different for these two variables.

Special cases when deriving dose_target_cut:

There are some special cases when deriving dose_target_cut when the underlying DLT rate (true_dlt_rate) and prob_target_cut are just off:

  • All doses are too toxic and belong to overdose interval. Then both dose_target_cut and dose_target_idx will be set to c(0, 0), indicating no doses are found for target/over dose interval and hence no index are reported.

  • All doses are in target dose interval, then dose_target_cut[2] will be set to the max dose in dose_grid.

  • All doses are either in target dose interval or overdose interval, with at least one in target dose interval and none in underdose interval. Then both dose_target_cut[1] and dose_target_idx[1] will be set to 0, indicating no cutting dose are found for under/target interval and hence no index are reported

Note: you can see that here we use 0 in dose_target_cut and dose_target_idx to indicate NA. This is for compatibility with later processing functions.