scholarly journals The study of waiting time to first pregnancy in the south of Iran: A parametric frailty model approach

2017 ◽  
Vol 15 (1) ◽  
pp. 11-16
Author(s):  
Najaf Zare ◽  
Bijan Nouri ◽  
Fariba Moradi ◽  
Maryam Parvareh ◽  
◽  
...  
Keyword(s):  
Waiting Time ◽  
Frailty Model ◽  
The South ◽  
Parametric Frailty ◽  
Model Approach

scholarly journals Parametric Frailty Model with Time-Dependent Covariates

2020 ◽  
Vol 8 (5) ◽  
pp. 952-956
Keyword(s):  
Goodness Of Fit ◽  
Random Effect ◽  
Real Life ◽  
Frailty Model ◽  
Information Criterion ◽  
Monte Carlo Integration ◽  
Time Dependent ◽  
Estimation Of Parameters ◽  
Time Dependent Covariates ◽  
Parametric Frailty

The parametric frailty model has been used in this study where, the term frailty is used to represent an unobservable random effect shared by subjects with similar (unmeasured) risks in the analysis of mortality rate. In real-life environment, the application of frailty models have been widely used by biostatistician, economists and epidemiologist to donate proneness to disease, accidents and other events because there are persistent differences in susceptibility among individuals. When heterogeneity is ignored in a study of survival analysis the result will produce an incorrect estimation of parameters and standard errors. This study used gamma and Weibull distribution for the frailty model. The first objective of this study is to investigate parametric model with time dependent covariates on frailty model. The derivation is using either classical maximum likelihood or Monte Carlo integration. The second objective is to measure the effectiveness of Gamma and Weibull frailty model with and without time-dependent covariates. This is done by calculating the root mean square error (RMSE). The last objective is to assess the goodness of fit of Gamma and Weibull frailty model with and without time-dependent covariates using Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC). Simulation is used in order to obtain the RMSE, AIC ad BIC value if time-dependent covariate does not exists. Between both models with time-dependent covariate, Weibull frailty distribution has lower AIC and BIC compared to Gamma frailty distribution. Therefore, Weibull frailty distribution with time-dependent covariate is preferable when a time-dependent covariate exists in a data.

scholarly journals An efficient and accurate frailty model approach for genome-wide survival association analysis controlling for population structure and relatedness in large-scale biobanks

2020 ◽  
Author(s):  
Rounak Dey ◽  
Wei Zhou ◽  
Tuomo Kiiskinen ◽  
Aki Havulinna ◽  
Amanda Elliott ◽  
...  
Keyword(s):  
Population Structure ◽  
Association Analysis ◽  
Large Scale ◽  
Computational Cost ◽  
Low Frequency ◽  
Saddlepoint Approximation ◽  
Frailty Model ◽  
Uk Biobank ◽  
Genome Wide ◽  
Model Approach

AbstractWith decades of electronic health records linked to genetic data, large biobanks provide unprecedented opportunities for systematically understanding the genetics of the natural history of complex diseases. Genome-wide survival association analysis can identify genetic variants associated with ages of onset, disease progression and lifespan. We developed an efficient and accurate frailty (random effects) model approach for genome-wide survival association analysis of censored time-to-event (TTE) phenotypes in large biobanks by accounting for both population structure and relatedness. Our method utilizes state-of-the-art optimization strategies to reduce the computational cost. The saddlepoint approximation is used to allow for analysis of heavily censored phenotypes (>90%) and low frequency variants (down to minor allele count 20). We demonstrated the performance of our method through extensive simulation studies and analysis of five TTE phenotypes, including lifespan, with heavy censoring rates (90.9% to 99.8%) on ~400,000 UK Biobank participants with white British ancestry and ~180,000 samples in FinnGen, respectively. We further performed genome-wide association analysis for 871 TTE phenotypes in UK Biobank and presented the genome-wide scale phenome-wide association (PheWAS) results with the PheWeb browser.

A Non-parametric Frailty Model for Temporally Clustered Multivariate Failure Times

2003 ◽  
Vol 30 (3) ◽  
pp. 523-533 ◽  
Author(s):  
Tommi Harkanen ◽  
Hannu Hausen ◽  
Jorma I. Virtanen ◽  
Elja Arjas
Keyword(s):  
Frailty Model ◽  
Failure Times ◽  
Multivariate Failure Times ◽  
Parametric Frailty ◽  
Non Parametric

Modelling of Breast Cancer Survival Data: A Frailty Model Approach

2011 ◽  
Vol 3 (10) ◽  
pp. 1-3
Author(s):  
Pari Dayal L Pari Dayal L ◽  
◽  
Leo Alexander T Leo Alexander T ◽  
Ponnuraja C Ponnuraja C ◽  
Venkatesan P Venkatesan P
Keyword(s):  
Breast Cancer ◽  
Survival Data ◽  
Cancer Survival ◽  
Frailty Model ◽  
Breast Cancer Survival ◽  
Cancer Survival Data ◽  
Model Approach

Bayesian non-parametric frailty model for dependent competing risks in a repairable systems framework

2020 ◽  
Vol 204 ◽  
pp. 107145
Author(s):  
Marco Pollo Almeida ◽  
Rafael S. Paixão ◽  
Pedro L. Ramos ◽  
Vera Tomazella ◽  
Francisco Louzada ◽  
...  
Keyword(s):  
Competing Risks ◽  
Frailty Model ◽  
Repairable Systems ◽  
Dependent Competing Risks ◽  
Systems Framework ◽  
Parametric Frailty ◽  
Non Parametric

A frailty model approach for regression analysis of multivariate current status data

2009 ◽  
Vol 28 (27) ◽  
pp. 3424-3436 ◽  
Author(s):  
Man-Hua Chen ◽  
Xingwei Tong ◽  
Jianguo Sun
Keyword(s):  
Regression Analysis ◽  
Frailty Model ◽  
Current Status Data ◽  
Current Status ◽  
Status Data ◽  
Model Approach

scholarly journals Semi-parametric frailty model for clustered interval-censored data

2016 ◽  
Vol 16 (5) ◽  
pp. 360-391 ◽  
Author(s):  
Aysun Çetinyürek Yavuz ◽  
Philippe Lambert
Keyword(s):  
Censored Data ◽  
Frailty Model ◽  
Interval Censored Data ◽  
Interval Censored ◽  
Parametric Frailty

scholarly journals Check-in Services and Passengers’ Impression of Airports in South-south Geopolitical Zone of Nigeria

2019 ◽  
pp. 1-10
Author(s):  
Eze, Felix John ◽  
Inyang, Juliet John
Keyword(s):  
Service Quality ◽  
Customer Service ◽  
Waiting Time ◽  
Linear Regression Analysis ◽  
Developed Countries ◽  
Multiple Linear Regression Analysis ◽  
The South ◽  
Frontline Staff ◽  
International Airport ◽  
Port Harcourt

The study examined check-in service quality attributes and passengers' impression of airports in the South-South geopolitical zone of Nigeria. The research was motivated by the desire to know how well passengers' impression of Nigerian airport service quality have been shaped by four check-in service attributes (competence of staff, politeness of staff, waiting time at check-in counters and interactions with passengers). The study used stratified random sampling to survey four hundred passengers at Port Harcourt International Airport and Margaret Ekpo International Airport. Data were collected using a five-point Likert scale questionnaire. The instrument was content-validated, while the Cronbach Alpha coefficient for the constructs gave reliability of 96.9 per cent. The data generated were analysed using mean rating and multiple linear regression analysis. The findings revealed that politeness of staff, waiting time at check-in counters and interactions with passengers significantly influenced passengers' impression of airports in the South-South geopolitical zone of Nigeria. The study recommended that Airport management should regularly train frontline staff on customer service communication skills; provide feedback mechanisms such as voice recorders and CCTV cameras to check front-line interactions with passengers, and automate the check-in process as is obtainable in developed countries to reduce the waiting time at check-in counters. These will ensure and improve passengers’ perception and patronage of aviation services in the zone, locally and internationally.

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