# FindLogisticGrids: FindLogisticGrids In dr4pl: Dose Response Data Analysis using the 4 Parameter Logistic (4pl) Model

## Description

Compute the grids on the upper and lower asymptote parameters for the logistic method based on initial parameter estimates and data.

## Usage

 `1` ```FindLogisticGrids(x, y, retheta.init, use.Hessian = FALSE) ```

## Arguments

 `x` Vector of doses. `y` Vector of responses. `retheta.init` Parameters of a 4PL model among which the EC50 parameter is in the log 10 dose scale. `use.Hessian` Indicator of whether the Hessian matrix (TRUE) or the gradient vector is used in confidence interval computation.

## Details

This function computes the grids on the upper and lower asymptote parameters based on initial parameter estimates and data. It basically computes the confidence intervals of the true parameters based on the variance-covariance matrix of the given initial parameter estimates. If matrix inversion of the variance-covariance matrix is infeasible, a variation of the method in Wang et al. (2010) is used.

## Value

Data frame whose first column represents the grid on the upper asymptote parameter and second column represents the grid o the lower asymptote.

Hyowon An

## References

\insertRef

Wang2010dr4pl

`FindHillBounds`, `FindInitialParms`