# hill_utils: Functions to solve the Hill model In USEPA/CompTox-ToxCast-tcpl: ToxCast Data Analysis Pipeline

## Description

These functions solve for Hill model parameters.

## Usage

 ```1 2 3 4 5``` ```tcplHillACXX(XX, tp, ga, gw, bt = 0) tcplHillConc(val, tp, ga, gw, bt = 0) tcplHillVal(logc, tp, ga, gw, bt = 0) ```

## Arguments

 `XX` Numeric, the activity level (percentage of the top value) `tp` Numeric, the top value from the Hill model `ga` Numeric, the logAC50 value from the Hill model `gw` Numeric, the Hill coefficient from the Hill model `bt` Numeric, the bottom value from the Hill model `val` Numeric, the activity value `logc` Numeric, the log concentration

## Details

`tcplHillVal` computes the value of the Hill model for a given log concentration.

`tcplHillACXX` computes the activity concentration for a Hill model for a given activity level.

`tcplHillConc` computes the Hill model concentration for a given value.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25``` ```## The following code gives examples for a Hill model with a top of 50, ## bottom of 0, AC50 of 1 and Hill coefficient of 1. ## tcplHillVal calculates activity value given a concentration. tcplHillVal ## will return the tp/2 when logc equals ga: tcplHillVal(logc = 1, tp = 50, ga = 1, gw = 1, bt = 0) ## Here, tcplHillConc returns the concentration where the value equals 20 tcplHillConc(val = 20, tp = 50, ga = 1, gw = 1, bt = 0) ## Note how this differs from tcplHillACXX: tcplHillACXX(XX = 20, tp = 50, ga = 1, gw = 1, bt = 0) ## tcplHillACXX is based on the top value and allows the user to calculate ## specifc activity concentrations based on a percentage of the top value ## For example, we can calculate the value for the concentration 0.25, then ## use that value to check the other two functions. value <- tcplHillVal(logc = 0.25, tp = 50, ga = 1, gw = 1, bt = 0) c1 <- tcplHillConc(val = value, tp = 50, ga = 1, gw = 1, bt = 0) c2 <- tcplHillACXX(XX = value/50*100, tp = 50, ga = 1, gw = 1, bt = 0) all.equal(0.25, c1, c2) ## Notice, the value had to be transformed to a percentage of the top value ## when using tcplHillACXX ```

USEPA/CompTox-ToxCast-tcpl documentation built on May 5, 2019, 4:48 p.m.