MLDS (version 0.5.1)

SimMLDS: Simulate Output of MLDS Experiment

Description

Given a block of trials of an MLDS experiment, an underlying response function and the judgment variability, simulate the response of an observer.

Usage

SimMLDS(Trials, Scale, Sigma, n = 1)

Value

If the argument n is set to 1 (default), an object of class ‘mlds.df’ or ‘mlbs.df’ with simulated responses. If n is greater than 1, a list of such objects is returned.

Arguments

Trials

an N by 4 or 3 matrix or data frame of integers indicating the n trials of an MLDS experiment. The columns indicate the indices of the stimuli presented on a trial, 4 for an experiment with quadruples and 3 for triads. A data frame for this argument is most easily generated with the combn function.

Scale

a vector of values indicating the underlying responses of the simulated observer for each stimulus level. The length of this vector should equal the largest integer in Trials.

Sigma

a vector of length 1 indicating the judgment standard deviation of the simulated observer.

n

integer giving number of simulated data sets to return

Author

Kenneth Knoblauch and Laurence T. Maloney

Details

Given a data frame of indices to the responses associated with stimulus levels and the judgment variability, the function returns the results of 1 or multiple MLDS experiments, either with triads or quads, depending on the number of columns in the data frame.

References

Maloney, L. T. and Yang, J. N. (2003). Maximum likelihood difference scaling. Journal of Vision, 3(8):5, 573--585, tools:::Rd_expr_doi("10.1167/3.8.5").

Knoblauch, K. and Maloney, L. T. (2008) MLDS: Maximum likelihood difference scaling in R. Journal of Statistical Software, 25:2, 1--26, tools:::Rd_expr_doi("10.18637/jss.v025.i02").

See Also

see also boot.mlds

Examples

Tr <- t(combn(10, 4))
Sc <- seq(0, 1, len = 11)^2
Sig <- 0.2
sim.lst <- SimMLDS(Tr, Sc, Sig, n = 10)
sim.res <- sapply(sim.lst, mlds)