Contents
What is a conditional power analysis?
Conditional power is an approach that quantifies the probability of rejecting the null hypothesis of no effect once some data are available. If this quantity is very small, a conclusion can be reached that it would be futile to continue the investigation.
What is a conditional power?
Conditional power (CP) is the probability that the final study result will be statistically significant, given the data observed thus far and a specific assumption about the pattern of the data to be observed in the remainder of the study, such as assuming the original design effect, or the effect estimated from the …
What is conditional power in clinical trials?
Conditional power is the probability that the final study result will be statistically significant, and it takes into account the interim results of treatment effect and the distribution of future treatment responses.
What is conditional power interim analysis?
Conditional power (a frequentist concept) is the probability that the final result will be significant, given the data obtained up to the time of the interim look.
When should I stop RCT?
RCTs can end when they reach their sample size goal, their event count goal, their length of follow-up goal, or when they reach their scheduled date of closure. In these situations the trial will stop in a manner independent of its results, and stopping is unlikely to introduce bias in the results.
What is a futility boundary?
A futility boundary (futility stopping boundary, rarely futility limit) is a statistical decision boundary used in sequential testing such as an AGILE A/B test. It is built in such a way that it maintains the type II error probability (beta β) larger than a specified level, on average.
What is futility test?
The term ‘futility’ is used to refer to the inability of a clinical trial to achieve its objectives. In particular, stopping a clinical trial when the interim results suggest that it is unlikely to achieve statistical significance can save resources that could be used on more promising research.
What is futility index?
One method of sequential analysis that has intuitive appeal for many medical investigators is based on the calculation of what we have termed the futility index, defined as the conditional probability that the trial will fail to demonstrate the superiority of the innovation given the results already observed [24,25].
Which is a function of the conditional power?
Conditional power is the probability of rejecting a false null hypothesis given the data that has been obtained so far. It is a function of the effect size and the data that have been collected.
When to use conditional power in futility assessment?
Conditional power is an approach that quantifies the probability of rejecting the null hypothesis of no effect once some data are available. If this quantity is very small, a conclusion can be reached that it would be futile to continue the investigation.
When to use power analysis in a study?
Additionally, power analysis can be used to determine power, given an effect size and the number of subjects available. You might do this when you know, for example, that only 75 subjects are available (or that you only have the budget for 75 subjects), and you want to know if you will have enough power to justify actually doing the study.
What happens if a power analysis is incorrect?
If any of these assumptions or guesses are incorrect, you may have less power than you need to detect the effect. Finally, because power analyses are based on assumptions and educated guesses, you often get a range of the number of subjects needed, not a precise number.