lik6pt {MLDS} | R Documentation |
The 6-point test evaluates the validity of the estimated difference scale. Given 6 values, a, b, c, a', b', c', on the stimulus scale, if the pair (a, b) > (a', b') and (b, c) > (b', c') then it must be that (a, c) > (a', c'), where the symbol > is taken here to mean “is judged more different than”. Given the observer's difference scale and σ estimate, the likelihood of the choices made is calculated based on the link function indicated in the ‘mlds’ object.
lik6pt(x, Six.Pts, ...)
x |
an object of class 'mlds', typically created by mlds |
Six.Pts |
a list of 3 data.frames, with names A , B , E . Each data.frame corresponds to a sample from a difference scaling experiment. The corresponding rows of the three data.frames yield the triples of trials that provide a 6-point test. The list can be constructed with the function GetSixPts . |
... |
currently unused. |
Returns the likelihood of the observer's responses for all of the 6-point conditions from a given data set. As currently implemented, it returns a 1x1 matrix.
Kenneth Knoblauch, based on C code by Laurence T. Maloney and J. N. Yang.
Maloney, L. T. and Yang, J. N. (2003). Maximum likelihood difference scaling. Journal of Vision, 3(8):5, 573–585, http://journalofvision.org/3/8/5/, doi:10.1167/3.8.5.
data(kk1) x.df <- mlds(SwapOrder(kk1)) lik6pt(x.df, Get6pts(x.df))