Description Usage Arguments Details Value Author(s) Examples

Test for changes in the level of statistical significance resulting from the deletion of potentially influential observations

1 |

`estex` |
Object of class 'estex', as returned from the |

`test` |
Value of the test statistic against which statistical significance is to be evaluated |

`parameters` |
Vector specifying the parameter(s) of which the significance is to be evaluated. If left unspecified, all parameters of the model are evaluated |

`sort` |
Specify whether the output should be sorted on the (absolute) magnitude of the test statistic after deletion of potentially influential cases |

`to.sort` |
If |

The `"sigtest"`

function tests whether excluding the influence of a single case changes the statistical significance of any or more variables in the model. This test of significance is based on the test statistic provided by the lme4 package. The nature of this statistic varies between different distributional families in the generalized mixed effects models. For instance, the t-statistic is related to a normal distribution while the z-statistic is related to binomial distributions.

For each of the cases that are evaluated, the test statistic of each variable is compared to a test-value specified by the user. For the purpose of this test, the parameter is regarded to statistically significant if the test statistic of the model exceeds the specified value. The `"sigtest"`

function reports for each variable the test statistic after deletion of each evaluated case, whether or not this updated test statistic results in statistical significance based on the user-specified value, and whether or not this new statistical significance differs from the significance in the original model. So, in other words, if a parameter was statistically significant in the original model, but is not longer significant after the deletion of a specific case from the model, this is indicated by the output of the `"sigtest"`

function. It is also indicated when an estimate was not significant originally, but reached statistical significance after deletion of a specific case.

Returns a list. For each variable in the original model that was evaluated, this list contains a matrix showing the test statistic from the original model (column 1), the test statistic after a potentially influential case was excluded from the model (column 2) and the result (TRUE / FALSE) of the test whether statistical significance changed as a result from deletion of (potentially) influential cases.

Rense Nieuwenhuis, Manfred te Grotenhuis, Ben Pelzer

1 2 3 4 5 6 7 8 9 10 11 |

```
Loading required package: lme4
Loading required package: Matrix
Attaching package: 'influence.ME'
The following object is masked from 'package:stats':
influence
Altered.Teststat Altered.Sig Changed.Sig
6053 -1.2991445 FALSE FALSE
6327 -1.6403859 FALSE FALSE
6467 -1.5623107 FALSE FALSE
7194 -1.5159431 FALSE FALSE
7472 -2.6299167 TRUE TRUE
7474 -2.0072703 TRUE TRUE
7801 -1.5219275 FALSE FALSE
7829 -0.9758367 FALSE FALSE
7930 -1.5280837 FALSE FALSE
24371 -1.5172395 FALSE FALSE
24725 -1.6177512 FALSE FALSE
25456 -1.5499640 FALSE FALSE
25642 -1.5337357 FALSE FALSE
26537 -1.3716896 FALSE FALSE
46417 -1.5976418 FALSE FALSE
47583 -1.5128142 FALSE FALSE
54344 -1.1132383 FALSE FALSE
62821 -1.0657896 FALSE FALSE
68448 -1.7024754 FALSE FALSE
68493 -1.5309190 FALSE FALSE
72080 -1.5268782 FALSE FALSE
72292 -1.5465888 FALSE FALSE
72991 -1.5788992 FALSE FALSE
```

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