Regarding the data_simulation.Rmd file

[zhiiiyang]

Hi, I have a few thoughts about improving the vignette data_simulation.Rmd file for your consideration.

• add some texts to explain how to convert median survival time to lambda in the create_event_dist function. It would be something like lambda is equal to log(2)/median survival time, e.g., if survival time is equal to 24 months, lambda is set to be log(2)/24.

  psborrow2/vignettes/data_simulation.Rmd

  Line 213 in 5123a8c

  exponential_dist <- create_event_dist(dist = "exponential", lambda = 1 / 24)

• remove the lines associated with external control in the section " Using fixed external data"

  psborrow2/vignettes/data_simulation.Rmd

  Lines 582 to 600 in 5123a8c

  	my_data_sim_setup_with_fixed <- create_data_simulation(
  	baseline = my_internal_baseline,
  	coefficients = c(age = 0.001, score_high = 1.1),
  	event_dist = create_event_dist(dist = "exponential", lambdas = 1 / 50),
  	fixed_external_data = historical_trial_data
  	) %>%
  	set_enrollment(
  	internal = enrollment_constant(rate = c(25, 10), for_time = c(4, 30)),
  	external = enrollment_constant(rate = c(30, 10), for_time = c(4, 30))
  	) %>%
  	set_dropout(
  	internal_treated = create_event_dist(dist = "exponential", lambdas = 1 / 50),
  	internal_control = create_event_dist(dist = "exponential", lambdas = 1 / 55),
  	external_control = create_event_dist(dist = "exponential", lambdas = 1 / 40)
  	) %>%
  	set_cut_off(
  	internal = cut_off_after_first(time = 60),
  	external = cut_off_after_events(n = 100)
  	)

• only count the number of events for cut_off_after_events described in cut off after events #279
  

  psborrow2/R/simulate_data.R

  Line 328 in 5123a8c

  cut_time <- sort(data$enrollment + data$eventtime)[n]

• Using a cutoff value to dichotomize a continuous variable to a binary variable is not needed since it is pretty straightforward for users to do it instead.

• I just noticed that you have introduced enrollment_constant function in earlier sections so I think the additional texts are not needed then.