triangle {sensR} | R Documentation |
Creates af copy of the binomial family with the inverse link function changed to equal the triangle psychometric function and correspondingly changed link function and derivative of the inverse link function.
triangle()
A binomial family object for models. Among other things it inludes the psychometric function as
linkinv
and the inverse psychometric function (for direct dprime computation) as
linkfun
.
Several functions in this package makes use of the function, but it may also be used on its own—see the example below.
Rune Haubo B Christensen and Per Bruun Brockhoff
Brockhoff, P.B. and Christensen, R.H.B. (2010). Thurstonian models for sensory discrimination tests as generalized linear models. Food Quality and Preference, 21, pp. 330-338.
duotrio
, twoAFC
,
threeAFC
, discrim
,
discrimPwr
, discrimSim
,
AnotA
, discrimSS
,
samediff
, findcr
xt <- matrix(c(10, 5), ncol = 2) ## data: 10 correct answers, 5 incorrect res <- glm(xt ~ 1, family = triangle) summary(res) ## Extended example plotting the profile likelihood ## data: 10 correct answers, 9 incorrect xt <- matrix(c(10, 9), ncol = 2) summary(res <- glm(xt ~ 1, family = triangle)) N <- 100 dev <- double(N) delta <- seq(1e-4, 3, length = N) for(i in 1:N) dev[i] <- glm(xt ~ -1 + offset(delta[i]), family = triangle)$deviance plot(delta, exp(-dev/2), type = "l", xlab = expression(delta), ylab = "Normalized Profile Likelihood") ## Add Normal approximation: lines(delta, exp(-(delta - coef(res))^2 / (2 * vcov(res))), lty = 2) ## Add confidence limits: level <- c(0.95, 0.99) lim <- sapply(level, function(x) exp(-qchisq(x, df=1)/2) ) abline(h = lim, col = "grey")