AccelStab (version 2.1.1)

step1_down_basic: Basic version Step1 Down Model

Description

Quickly fit the one-step Šesták–Berggren kinetic model.

Usage

step1_down_basic(
  data,
  y,
  .time,
  K = NULL,
  C = NULL,
  validation = NULL,
  parms = NULL,
  reparameterisation = FALSE,
  zero_order = FALSE
)

Value

The fit object

Arguments

data

Dataframe containing accelerated stability data (required).

y

Name of decreasing variable (e.g. concentration) contained within data (required).

.time

Time variable contained within data (required).

K

Kelvin variable (numeric or column name) (optional).

C

Celsius variable (numeric or column name) (optional).

validation

Validation dummy variable, the column must contain only 1s and 0s, 1 for validation data and 0 for fit data. (column name) (optional).

parms

Starting values for the parameters as a list - k1, k2, k3, and c0.

reparameterisation

Use alternative parameterisation of the one-step model which aims to reduce correlation between k1 and k2.

zero_order

Set kinetic order, k3, to zero (straight lines).

Details

Fit the one-step Šesták–Berggren kinetic (non-linear) model using accelerated stability data from an R dataframe format. Fit summary is printed to the console and the fit itself is returned. Fewer arguments and outputs than the main function for rapid testing. Parameters are kept in even when not significant.

Examples

#load antigenicity and potency data.
data(antigenicity)
data(potency)

#Use of the step1_down_basic function with C column defined.
fit1 <- step1_down_basic(data = antigenicity, y = "conc", .time = "time", C = "Celsius")

#Basic use of the step1_down_basic function with K column defined & Validation data segmented out.
fit2 <- step1_down_basic(data = antigenicity, y = "conc", .time = "time", K = "K",
validation = "validA")

#When zero_order = FALSE, the output suggests using zero_order = TRUE for Potency dataset.
fit3 <- step1_down_basic(data = potency, y = "Potency", .time = "Time",C = "Celsius",
  reparameterisation = FALSE, zero_order = TRUE)

#reparameterisation is TRUE.
fit4 <- step1_down_basic(data = antigenicity, y = "conc", .time = "time",C = "Celsius",
  reparameterisation = TRUE)