Our Road Map

We are always growing our tool set to provide you with anything you might need to design your study. Below is a list of recently added tools and tools that we will be adding soon. If you have any questions, or don't see a tool you need, let us know! Your feed back is important for us to provide you with the support you need.

Upcoming Functionality:

Export Calculation Reports to PDF
Currently, we offer csv (Excel) downloads for the output of the calculators, randomization list generators and design generators. We are currently working supporting exporting the output to pdf files which will include an overview of the method used and references. In the case of power and sample size it will also include a text snippet describing the result of the calculation for paper and grant submissions.
Finite Population Adjustments
Currently, our power and sample size calculators assume the population from which the samples are take are infinite. If you know the population however, this has the effect of inflating the sample size/deflating the power of a test. To correct this, you can apply the finite population correction, given by \(\frac{N - n}{N - 1}\) where \(n\) and \(N\) are the sample and total population respectively. We are working on adding the ability to make this correction to all power and sample size calculations.
Group Sequential Testing Adjustments
Early stopping rules and interim analyses are commonly used techniques to ensure that a study is going well or that it is abandoned at the appropriate time if it is going poorly. These rules and analyses need to be planed in advance due to their effect on the overall \(\alpha\)-level of the study. We will be adding support to our calculators to ensure that the study is appropriately planned.

Upcoming Tools:

Two Sample test of Means with Unequal Variances
Currently, the two sample test of means assumes that the variance of the two samples is the same. This often does not hold up in practice, so we are adding a calculator to deal with the case that the variances are unequal.
Additional Designs for Population Bioequivalence
Our current calculator for the power of a test of population bioequivalence assumes as 2 by 2 crossover design, as recommended by the FDA. However there are other designs that are possible to test hypotheses on population bioequivalence. We will be adding options to the calculator for a 2 by 4 and a 2 by 3 crossover.
Individual and in-vitro Bioequivalence
We will be adding calculators for testing both individual and in-vitro bioequivalence.
Power and Sample Size Calculators for ROC Curve
ROC Curves are commonly used in statistical learning theory/machine learning to evaluate and compare models that differentiate between groups. We will be adding power and sample size calculators for comparing the AUC under a single ROC curve to a fixed value as well as comparing the AUCs of two ROC curves.
Bayesian Methods for Sample Size calculation
Bayesian sample size calculation looks at how many subjects are needed to estimate a given quality of the posterior distribution. One such method finds the sample size needed to find a posterior interval of a given length, \(l\), under an appropriate coverage criterion and prior distribution. We will be adding calculators that support these methods for one sample and two-sample tests of means.

This list represents our focus for the next several additions to the site, but we have more coming after these. If you don't see the tool or functionality you need, let us know!

See our Plans and Pricing