# Ffun: Compute the negative log likelihoods associated with a vector... In TestGardener: Information Analysis for Test and Rating Scale Data

 Ffun R Documentation

## Compute the negative log likelihoods associated with a vector of score index values.

### Description

Ffun computes the negative log likelihoods for a set of examinees, each at a single value index.

### Usage

``````  Ffun(index, SfdList, chcemat)
``````

### Arguments

 `index` A vector of size `N` containing values for score indices in the interval [0,100]. `SfdList` A numbered list object produced by a TestGardener analysis of a test. Its length is equal to the number of items in the test or questions in the scale. Each member of `SfdList` is a named list containing information computed during the analysis. `chcemat` An `N` by `n` matrix of responses or, for a single examinee, a vector of length `n`.

### Value

A vector of length `N` of negative log likelihood values.

### Author(s)

Juan Li and James Ramsay

### References

Ramsay, J. O., Li J. and Wiberg, M. (2020) Full information optimal scoring. Journal of Educational and Behavioral Statistics, 45, 297-315.

Ramsay, J. O., Li J. and Wiberg, M. (2020) Better rating scale scores with information-based psychometrics. Psych, 2, 347-360.

```make_dataList, index_fun, Ffun, Ffuns_plot ```

### Examples

``````  #  Example 1:  Compute the values of the objective function for locating each
#  examinee or respondent for the 24-item short form of the SweSAT quantitative
#  test on the percentile score index continuum [0,100].
#  Use only the first five examinees
chcemat <- Quant_13B_problem_dataList\$chcemat
SfdList <- Quant_13B_problem_parmList\$SfdList
index   <- Quant_13B_problem_parmList\$index
Fval    <- Ffun(index[1:5], SfdList, chcemat[1:5,])
``````

TestGardener documentation built on May 29, 2024, 3:31 a.m.