Milestones: Class of Milestones

In TrialSimulator: Clinical Trial Simulator

Class of Milestones

Description

Create a class of milestone. A milestone means the time point to take an action, e.g., carrying out (futility, interim, final) analysis for adding/removing arms, or stopping a trial early. It can also be any more general time point where trial data is used in decision making or adaptation. For example, one can define a milestone for changing randomization scheme, sample size re-assessment, trial duration extension etc.

Public methods in this R6 class are used in developing this package. Thus, we have to export the whole R6 class which exposures all public methods. However, none of the public methods on this page is useful to end users. Instead, refer to the vignette to learn how to define milestones when performing simulation using TrialSimulator.

Value

an R6Class generator object; use milestone() to create a milestone.

Methods

Public methods

• Milestones$new()

• Milestones$get_name()

• Milestones$set_trigger_condition()

• Milestones$set_action_function()

• Milestones$get_trigger_status()

• Milestones$reset()

• Milestones$trigger_milestone()

• Milestones$mute()

• Milestones$clone()

---

Method new()

initialize milestone

Usage

Milestones$new(name, type = name, trigger_condition, action = doNothing, ...)

Arguments

name

character. Name of milestone.

type

character vector. Milestone type(s) (futility, interim, final), a milestone can be of multiple types. This is for information purpose so can be any string.

trigger_condition

function to check if this milestone should trigger. See vignette Condition System for Triggering Milestones in a Trial.

action

function to execute when the milestone triggers.

...

(optional) arguments of action.

---

Method get_name()

INTERNAL MACHINERY: DO NOT CALL THIS METHOD DIRECTLY.

return name of milestone

Usage

Milestones$get_name()

---

Method set_trigger_condition()

INTERNAL MACHINERY: DO NOT CALL THIS METHOD DIRECTLY.

replace the trigger condition of a not-yet-triggered milestone. This is invoked by the listener when it applies an update requested through Trials$update_milestone() within an action function. The as-designed condition, frozen at construction, is restored by reset() between simulation replicates.

Usage

Milestones$set_trigger_condition(trigger_condition)

Arguments

trigger_condition

an object of class Condition. See trigger_condition of milestone().

---

Method set_action_function()

INTERNAL MACHINERY: DO NOT CALL THIS METHOD DIRECTLY.

replace the action function (and its fixed arguments) of a not-yet-triggered milestone. This is invoked by the listener when it applies an update requested through Trials$update_milestone() within an action function. The action in effect at construction is restored by reset() between simulation replicates.

Usage

Milestones$set_action_function(action, action_args = list())

Arguments

action

function to execute when the milestone triggers. See action of milestone().

action_args

named list. Fixed arguments of action, corresponding to ... of milestone().

---

Method get_trigger_status()

INTERNAL MACHINERY: DO NOT CALL THIS METHOD DIRECTLY.

return trigger status

Usage

Milestones$get_trigger_status()

---

Method reset()

INTERNAL MACHINERY: DO NOT CALL THIS METHOD DIRECTLY.

reset an milestone so that it can be triggered again. Usually, this is called before the controller of a trial can run additional replicates of simulation. If the trigger condition or the action was replaced in-run through Trials$update_milestone(), the as-designed version is restored so that every replicate starts from the original design.

Usage

Milestones$reset()

---

Method trigger_milestone()

INTERNAL MACHINERY: DO NOT CALL THIS METHOD DIRECTLY.

trigger an milestone (always TRUE) and execute action accordingly. It calls Trial$get_data_lock_time() to lock data based on conditions implemented in Milestones$trigger_condition. If time that meets the condition cannot be found, Trial$get_data_lock_time() will throw an error and stop the program. This means that user needs to adjust their trigger_condition (e.g., target number of events (target_n_events) is impossible to reach).

Usage

Milestones$trigger_milestone(trial)

Arguments

trial

a Trial object.

---

Method mute()

INTERNAL MACHINERY: DO NOT CALL THIS METHOD DIRECTLY.

mute all messages (not including warnings)

Usage

Milestones$mute(silent)

Arguments

silent

logical.

---

Method clone()

The objects of this class are cloneable with this method.

Usage

Milestones$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

TrialSimulator documentation built on Sept. 4, 2026, 5:08 p.m.