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Release Notes

drda 2.0.4

• Fitted values and residuals have now the correct length even when there are zero weights.
• Fixed a bug when calculating the variance for models with fixed parameters.
• Function predict can now return standard errors and prediction intervals.
• Upgraded Roxygen2 to version 7.3.2.

drda 2.0.3

• Updated vignette after review from the Journal of Statistical Software.
• Fixed again the x-axis of the plot.

drda 2.0.2

• Fixed a bug in the plot when doses were not previously sorted.
• Fixed a bug in the x-axis of the plot when data contained zeros.
• It is now possible to not plot data points by setting option plot_data to FALSE (default TRUE).

drda 2.0.1

• Small fixes to unit tests because they were not passing on specific systems.
• Updated vignette with new simulation results.

drda 2.0.0

It is now possible to fit models using either the log-dose or the dose scale.

To accommodate this extension it was necessary to change the default model parameterization, which now follows that of the Emax model (Macdougall, 2006).

Briefly, the 5-parameter logistic function is now defined as

alpha + delta / (1 + nu * exp(-eta * (x - phi)))^(1 / nu)

Parameter alpha is the value of the function when x approaches -Inf. Parameter delta is the (signed) height of the curve. Parameter eta > 0 represents the steepness (growth rate) of the curve. Parameter phi is related to the mid-value of the function. Parameter nu affects near which asymptote maximum growth occurs.

Similarly, the newly implemented log-logistic function (when x >= 0) is defined as

alpha + delta * (x^eta / (x^eta + nu * phi^eta))^(1 / nu)

Check the vignette (vignette("drda", package = "drda")) or the help page (help(drda)) to know more about the available models.

Here is a change log from previous version:

• Change parameterization to follow that of the Emax model.
• Implement the log-logistic family of models.
• Improve initialization algorithm to be more efficient and (hopefully) robust.
• Exported functions for evaluating theoretical gradient and Hessian of each implemented model.
• Implement the effective_dose function for estimating effective doses.
• Added examples to help pages.
• Many minor bug fixes (too many to list them all).

drda 1.0.0

First public release.

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
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