sensR (version 1.2.2)

samediff: Computation of tau and dprime for same different test

Description

Computation of tau and dprime and their uncertainties for the same different test using maximum likelihood.

Usage

samediff(nsamesame, ndiffsame, nsamediff, ndiffdiff, VCOV = TRUE)

Arguments

nsamesame

The number of same-answers on same-samples

ndiffsame

The number of different-answers on same-samples

nsamediff

The number of same-answers on different-samples

ndiffdiff

The number of different-answers on different-samples

VCOV

Should the variance-covariance matrix of the parameters be computed. Defaults to TRUE.

Value

• An object of class samediff with elements
• coef
  named vector of coefficients (d-prime and tau)
• vcov
  variance-covariance matrix of the coefficients
• se
  named vector with standard error of the coefficients (standard error of d-prime)
• data
  a named vector with the data supplied to the function
• test
  a string with the name of the test (same-different)
• call
  the matched call
• convergence
  convergence indicater. 0 indicates convergence. For error codes see optim.
• logLik
  Value of the log-likelhood at the MLE of the parameters.
• case
  A case indicator for internal use

Details

The function computes the maximum likelihood estimates of tau and delta.

References

Christensen, R.H.B., Brockhoff, P.B. (2009). Estimation and inference in the same-different test. Food, Quality and Preference, 20 pp. 514--520

Examples

# data: 8 of the same samples were judged to be same
#       5 of the same samples were judged to be different
#       4 of the different samples were judged to be same
#       9 of the different samples were judged to be different

samediff(8, 5, 4, 9)