Finding logistic models to generate data with desired risk ratio, risk difference and AUC profiles

About two years ago, someone inquired whether simstudy had the functionality to generate data from a logistic model with a specific AUC. It did not, but now it does, thanks to a paper by Peter Austin that describes a nice algorithm to accomplish this. The paper actually describes a series of related algorithms for generating coefficients that target specific prevalence rates, risk ratios, and risk differences, in addition the AUC. [Read More]

simstudy 0.6.0 released: more flexible correlation patterns

The new version (0.6.0) of simstudy is available for download from CRAN. In addition to some important bug fixes, I’ve added new functionality that should make data generation with correlated data a little more flexible. In the previous post, I described enhancements to the function genCorMat. As part of this release announcement, I’m describing blockExchangeMat and blockDecayMat, two new functions that can be used to generate correlation matrices when there is a temporal element to the data generation. [Read More]

Flexible correlation generation: an update to genCorMat in simstudy

I’ve been slowly working on some updates to simstudy, focusing mostly on the functionality to generate correlation matrices (which can be used to simulate correlated data). Here, I’m briefly describing the function genCorMat, which has been updated to facilitate the generation of correlation matrices for clusters of different sizes and with potentially different correlation coefficients. I’ll briefly describe what the existing function can currently do, and then give an idea about what the enhancements will provide. [Read More]

simstudy updated to version 0.5.0

A new version of simstudy is available on CRAN. There are two major enhancements and several new features. In the “major” category, I would include (1) changes to survival data generation that accommodate hazard ratios that can change over time, as well as competing risks, and (2) the addition of functions to allow users to sample from existing data sets with replacement to generate “synthetic” data will real life distribution properties. [Read More]

simstudy update: ordinal data generation that violates proportionality

Version 0.4.0 of simstudy is now available on CRAN and GitHub. This update includes two enhancements (and at least one major bug fix). genOrdCat now includes an argument to generate ordinal data without an assumption of cumulative proportional odds. And two new functions defRepeat and defRepeatAdd make it a bit easier to define multiple variables that share the same distribution assumptions. Ordinal data In simstudy, it is relatively easy to specify multinomial distributions that characterize categorical data. [Read More]
R  simstudy 

simstudy update: adding flexibility to data generation

A new version of simstudy (0.3.0) is now available on CRAN and on the package website. Along with some less exciting bug fixes, we have added capabilities to a few existing features: double-dot variable reference, treatment assignment, and categorical data definition. These simple additions should make the data generation process a little smoother and more flexible. Using non-scalar double-dot variable reference Double-dot notation was introduced in the last version of simstudy to allow data definitions to be more dynamic. [Read More]
R  simstudy