# Create Discrimination Probabilities (Psi) from Data Frame

### Description

Creates matrices with discrimination probabilities, number of trials, number of different answers, and stimulus intensities from a data frame.

### Usage

1 |

### Arguments

`data` |
data frame with repeated same-different judgments. |

`oa1, oa2` |
name of the variable that contains the stimulus intensities in the first and second observation area. |

`resp` |
name of response variable for same-different judgments;
answers have to be |

### Details

The data frame must include at least a column for the response and one
column each for observation areas one and two. The return value of
`psi`

may serve as an input to `qdm`

that fits a
quadrilateral dissimilarity model to the judgments.

### Value

An object of class `psi`

that consists of the following components:

`prob` |
a matrix of discrimination probabilities per stimulus combination. |

`ntrials` |
a matrix of number of trials per stimulus combination. |

`freq` |
a matrix of frequencies of different answers per stimulus combination. |

`x, y` |
(if possible numeric) vectors of stimulus intensities. |

### See Also

`qdm`

.

### Examples

1 2 |