confint.twoAC | R Documentation |

Computes confidence intervals from the profiled likelihood and the Wald approximation in the 2AC model, or plots the profile likelihood function for d.prime.

```
## S3 method for class 'twoAC'
confint(object, parm, level = 0.95,
type = c("likelihood", "Wald"), ...)
## S3 method for class 'profile.twoAC'
confint(object, parm = "d.prime", level = 0.95, ...)
## S3 method for class 'twoAC'
profile(fitted, alpha = 1e-3, nSteps = 1e2, range, ...)
## S3 method for class 'profile.twoAC'
plot(x, level = c(0.95, 0.99), Log = FALSE,
relative = TRUE, fig = TRUE, n = 1e3, ..., ylim = NULL)
```

`object` |
a fitted |

`fitted` |
a fitted |

`x` |
a |

`type` |
the type of confidence interval required. |

`parm` |
For For |

`level` |
the confidence level required. |

`alpha` |
determines the range of profiling. By default the likelihood is profiled in the 99.9% Wald confidence interval region. |

`range` |
if supplied, |

`nSteps` |
the number of profile steps. |

`Log` |
should the profile likelihood be plotted on the log-scale? |

`relative` |
should the relative or the absolute likelihood be plotted? |

`fig` |
should the profile likelihood be plotted? |

`n` |
the no. points used in the spline interpolation of the profile likelihood. |

`ylim` |
overrules default y-limits on the plot of the profile likelihood. |

`...` |
not currently used. |

These `confint`

methods call
the appropriate profile method, then finds the
confidence intervals by interpolation of the profile traces.
If the profile object is already available, this should be used as the
main argument rather than the fitted model object itself.

In `plot.profile.twoAC`

: at least one of `Log`

and
`relative`

arguments have to be `TRUE`

.

`confint`

:
A matrix (or vector) with columns giving lower and upper confidence
limits for each parameter. These will be labelled as (1-level)/2 and
1 - (1-level)/2 in % (by default 2.5% and 97.5%).
Profile likelihood confindence intervals are only available for
`d.prime`

and not `tau`

.

`profile.twoAC`

: a `data.frame`

with the profile of
`d.prime`

.

`plot.profile.twoAC`

invisibly returns the spline approcimation to
the profile.

Rune Haubo B Christensen

Christensen R.H.B., lee H-S and Brockhoff P.B. (2012). Estimation of the Thurstonian model for the 2-AC protocol. Food Quality and Preference, 24(1), pp.119-128.

`profile`

and `confint`

```
(fm1 <- twoAC(c(2, 2, 6)))
confint(fm1)
confint(fm1, type = "Wald")
pr1 <- profile(fm1)
confint(pr1)
pr1 <- profile(fm1, alpha = 1e-5)
old <- par(mfrow = c(2,2))
plot(pr1)
plot(pr1, Log = FALSE, relative = TRUE)
plot(pr1, Log = TRUE, relative = TRUE)
plot(pr1, Log = TRUE, relative = FALSE)
par(old)
```

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