TestData {Dark}

Data that can be used to test other scripts.

Description

This script creates data in the form of a dark object from specified times, parameters, and level of variability. It is used for testing and developing other scripts. Presently only the seven parameter model and its subsets are implemented.

Usage

TestData(x, theta, sse, repeatable)

Arguments

x

the times at which observations are made.

theta

the parameters of the Mahroo Lamb Pugh model

theta :	parameter	default	Units
theta[1]:	cone threshold	-1	(log lum)
theta[2]:	cone coefficient	1	(log lum)
theta[3]:	cone time constant	1	(minutes)
theta[4]:	S2	-0.24	(log lum/ minute)
theta[5]:	alpha point	6	(minutes)
theta[6]:	-(S2 + S3)	0.20	(log luminance)
theta[7]:	beta point	13	(log luminance)

sse

the variability of the data

repeatable

a boolean flag that ensures that the function can return the same values each time it is called.

Details

The parameters values chosen as defaults are entirely arbitrary. The sixth parameter is the negative sum of the rates of rod recovery called S2 and S3

Value

The function returns a dark object with the following components;

call

a label describing the last call the object was subject to

time

the time observations

thrs

thresholds

resid

residuals

fit

thresholds predicted in the absence of noise

thet

parameters passed to the function

sse

the sum of squared residuals value used to describe the variability in the data

val

the actual sse of the generated data

data

the name of the data source

Author(s)

Jeremiah MF Kelly

Faculty of Life Sciences, The University of Manchester, M13 9PL, UK

References

L. Patryas, N. R. Parry, D. Carden, D. H. Baker, J. M. Kelly, T. Aslam, and I. J. Murray. Assessment of age changes and repeatability for computer-based rod dark adaptation. Graefe's Archive for Clinical and Experimental Ophthalmology, pages 1-7, 2013.

Examples

set.seed(1234)
x <- seq(0,20)
tmp <- TestData(x)
tmp