### Abstract

This article elaborates the results found in Petersen (1991) by discussing how to minimize time-aggregation bias in hazard-rate models with measured covariates. It first considers a model with a single categorical covariate with h categories. It derives analytically the bias of the estimator that assumes the durations are exactly measured, when the durations are in fact rounded up to the nearest integer. Second, the article conducts both large-and small-sample Monte Carlo studies for several estimators of the covariate effects in the presence of time aggregation. There are three central findings. (1) It is shown that the likelihood that adjusts for the grouped nature of the duration measures recaptures the parameters very well. (2) The estimator that assumes that the durations are exactly measured, when they in fact are rounded up to the nearest integer, is biased in several ways. (3) The estimator that uses the midpoint adjustment suffers from the same weaknesses as the estimator that rounds up to the nearest integer, but to a lesser degree.

Original language | English (US) |
---|---|

Pages (from-to) | 25-51 |

Number of pages | 27 |

Journal | Sociological Methods & Research |

Volume | 21 |

Issue number | 1 |

DOIs | |

State | Published - 1992 |

Externally published | Yes |

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### ASJC Scopus subject areas

- Social Sciences (miscellaneous)
- Sociology and Political Science

### Cite this

*Sociological Methods & Research*,

*21*(1), 25-51. https://doi.org/10.1177/0049124192021001002

**Time-Aggregation Bias in Hazard-Rate Models with Covariates.** / Petersen, Trond; Koput, Kenneth W.

Research output: Contribution to journal › Article

*Sociological Methods & Research*, vol. 21, no. 1, pp. 25-51. https://doi.org/10.1177/0049124192021001002

}

TY - JOUR

T1 - Time-Aggregation Bias in Hazard-Rate Models with Covariates

AU - Petersen, Trond

AU - Koput, Kenneth W

PY - 1992

Y1 - 1992

N2 - This article elaborates the results found in Petersen (1991) by discussing how to minimize time-aggregation bias in hazard-rate models with measured covariates. It first considers a model with a single categorical covariate with h categories. It derives analytically the bias of the estimator that assumes the durations are exactly measured, when the durations are in fact rounded up to the nearest integer. Second, the article conducts both large-and small-sample Monte Carlo studies for several estimators of the covariate effects in the presence of time aggregation. There are three central findings. (1) It is shown that the likelihood that adjusts for the grouped nature of the duration measures recaptures the parameters very well. (2) The estimator that assumes that the durations are exactly measured, when they in fact are rounded up to the nearest integer, is biased in several ways. (3) The estimator that uses the midpoint adjustment suffers from the same weaknesses as the estimator that rounds up to the nearest integer, but to a lesser degree.

AB - This article elaborates the results found in Petersen (1991) by discussing how to minimize time-aggregation bias in hazard-rate models with measured covariates. It first considers a model with a single categorical covariate with h categories. It derives analytically the bias of the estimator that assumes the durations are exactly measured, when the durations are in fact rounded up to the nearest integer. Second, the article conducts both large-and small-sample Monte Carlo studies for several estimators of the covariate effects in the presence of time aggregation. There are three central findings. (1) It is shown that the likelihood that adjusts for the grouped nature of the duration measures recaptures the parameters very well. (2) The estimator that assumes that the durations are exactly measured, when they in fact are rounded up to the nearest integer, is biased in several ways. (3) The estimator that uses the midpoint adjustment suffers from the same weaknesses as the estimator that rounds up to the nearest integer, but to a lesser degree.

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U2 - 10.1177/0049124192021001002

DO - 10.1177/0049124192021001002

M3 - Article

VL - 21

SP - 25

EP - 51

JO - Sociological Methods and Research

JF - Sociological Methods and Research

SN - 0049-1241

IS - 1

ER -