drfit was the first package on CRAN dedicated to dose-reponse curve fitting. Its first release to CRAN was made in July 2004. In December 2005, the wonderful drc package by Christian Ritz and Jens Streibig was published on CRAN. However, by that time our working group at the University of Bremen was already hooked on drfit.

We kept our raw dose-response data in a MySQL database, which was accessed using the ‘drdata’ function. Of course this only worked with a suitable configuration of the ODBC data source.

Functions that are fitted are the cumulative density function of the log-normal distribution (‘probit’ fit), of the logistic distribution (‘logit’ fit), of the Weibull distribution (‘weibull’ fit) and a linear-logistic model (‘linlogit’ fit), derived from the latter, which is used to describe data showing stimulation at low doses (hormesis). In addition, functions checking and plotting are included. As an alternative to the original fitting methods, the algorithms from the ‘drc’ package can be used.

More details can be found in the function reference.

The drfit package was archived on CRAN at my request on August 26, 2023. The last version that was published is 0.7.2.