# Modeling Secondary Phenotypes Conditional on Genotypes in Case–Control Studies

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## Abstract

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## 1. Introduction

## 2. Proposed Method

## 3. Simulation Study

#### 3.1. General Setup

#### 3.2. Continuous Phenotypes

#### 3.3. Ordinal Phenotypes

- $\beta =0.5$, ${\zeta}_{0}=1.5$, ${\zeta}_{1}=2.5$, and ${\gamma}_{1}={\gamma}_{2a}={\gamma}_{2b}=log\left(2\right)$
- $\beta =1$, ${\zeta}_{0}=0$, ${\zeta}_{1}=1$, and ${\gamma}_{1}={\gamma}_{2a}={\gamma}_{2b}=log\left(2\right)$
- $\beta =0.75$, ${\zeta}_{0}=1$, ${\zeta}_{1}=2$, and ${\gamma}_{1}={\gamma}_{2a}={\gamma}_{2b}=log\left(2\right)$
- $\beta =0.5$, ${\zeta}_{0}=1.5$, ${\zeta}_{1}=2.5$, ${\gamma}_{1}={\gamma}_{2a}=log\left(2\right)$, and ${\gamma}_{2b}=log\left(3\right)$.

#### 3.4. Time-to-Event Phenotypes

## 4. Data Application

## 5. Discussion

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## Abbreviations

OPPERA | Orofacial Pain: Prospective Evaluation and Risk Assessment |

TMD | Temporomandibular disorders |

IPW | Inverse probability weighting |

Q–Q | Quantile–quantile |

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Parameters | ${\mathit{\beta}}_{1}$ = −0.12 | ${\mathit{\beta}}_{1}$ = −0.12 | ${\mathit{\beta}}_{1}$ = −0.12 | ${\mathit{\beta}}_{1}$ = −0.12 | ${\mathit{\beta}}_{1}$ = −0.5 | ${\mathit{\beta}}_{1}$ = −1 | ${\mathit{\beta}}_{1}$ = −2 | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|

${\mathit{\gamma}}_{1}=log\left(2\right)$ | ${\mathit{\gamma}}_{1}=log\left(3\right)$ | ${\mathit{\gamma}}_{1}=log\left(5\right)$ | ${\mathit{\gamma}}_{1}=log\left(10\right)$ | ${\mathit{\gamma}}_{1}=log\left(2\right)$ | ${\mathit{\gamma}}_{1}=log\left(2\right)$ | ${\mathit{\gamma}}_{1}=log\left(2\right)$ | ||||||||

Bias | Cover | Bias | Cover | Bias | Cover | Bias | Cover | Bias | Cover | Bias | Cover | Bias | Cover | |

LM | −0.044 | 0.728 | 0.059 | 0.577 | 0.061 | 0.532 | 0.048 | 0.666 | 0.028 | 0.883 | 0 | 0.944 | −0.058 | 0.643 |

LM, controls only | −0.039 | 0.875 | −0.073 | 0.698 | −0.108 | 0.444 | −0.151 | 0.206 | −0.022 | 0.926 | −0.002 | 0.939 | 0.037 | 0.892 |

LM, cases only | −0.056 | 0.761 | −0.099 | 0.394 | −0.166 | 0.06 | −0.256 | 0 | −0.028 | 0.911 | 0.002 | 0.949 | 0.061 | 0.794 |

LM adjusted for case status | 0.048 | 0.696 | −0.088 | 0.235 | −0.14 | 0.021 | −0.208 | 0 | −0.025 | 0.877 | 0 | 0.945 | 0.047 | 0.736 |

Monsees | −0.002 | 0.950 | −0.001 | 0.951 | 0.001 | 0.948 | 0.001 | 0.949 | 0.001 | 0.952 | −0.001 | 0.938 | −0.003 | 0.949 |

Bootstrap | −0.002 | 0.950 | −0.001 | 0.956 | 0.001 | 0.944 | 0.001 | 0.946 | 0.001 | 0.950 | −0.001 | 0.937 | −0.003 | 0.944 |

CI Width (Valid Methods Only) | ||||||||||||||

Monsees | 0.164 | 0.160 | 0.155 | 0.148 | 0.166 | 0.167 | 0.168 | |||||||

Bootstrap | 0.162 | 0.160 | 0.154 | 0.147 | 0.165 | 0.167 | 0.168 |

Method | Result | |||||||
---|---|---|---|---|---|---|---|---|

Scenario 1 | Scenario 2 | Scenario 3 | Scenario 4 | |||||

Bias | Coverage | Bias | Coverage | Bias | Coverage | Bias | Coverage | |

Naive | −0.054 | 0.909 | −0.068 | 0.836 | −0.053 | 0.910 | −0.069 | 0.871 |

Controls only | 0.075 | 0.937 | 0.051 | 0.937 | 0.063 | 0.948 | 0.093 | 0.933 |

Cases only | 0.805 | 0 | −0.815 | 0 | 0.226 | 0 | 0.903 | 0 |

Adjusted for case status | 0.057 | 0.904 | 0.027 | 0.937 | 0.054 | 0.913 | 0.101 | 0.824 |

Bootstrap | 0.020 | 0.943 | 0.006 | 0.944 | 0.015 | 0.948 | 0.015 | 0.951 |

CI Width (Valid Methods Only) | ||||||||

Bootstrap | 0.519 | 0.399 | 0.477 | 0.512 |

Method | Bias | Coverage |
---|---|---|

Naive | −0.457 | 0.006 |

Controls only | 0.272 | 0.396 |

Cases only | −0.800 | 0.225 |

Adjusted for case status | 0.091 | 1.000 |

Bootstrap | −0.017 | 0.944 |

CI Width (Valid Methods Only) | ||

Bootstrap | 0.439 |

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## Share and Cite

**MDPI and ACS Style**

Brownstein, N.C.; Cai, J.; Smith, S.; Diatchenko, L.; Slade, G.D.; Bair, E.
Modeling Secondary Phenotypes Conditional on Genotypes in Case–Control Studies. *Stats* **2022**, *5*, 203-214.
https://doi.org/10.3390/stats5010014

**AMA Style**

Brownstein NC, Cai J, Smith S, Diatchenko L, Slade GD, Bair E.
Modeling Secondary Phenotypes Conditional on Genotypes in Case–Control Studies. *Stats*. 2022; 5(1):203-214.
https://doi.org/10.3390/stats5010014

**Chicago/Turabian Style**

Brownstein, Naomi C., Jianwen Cai, Shad Smith, Luda Diatchenko, Gary D. Slade, and Eric Bair.
2022. "Modeling Secondary Phenotypes Conditional on Genotypes in Case–Control Studies" *Stats* 5, no. 1: 203-214.
https://doi.org/10.3390/stats5010014