A Gamma-Generated Logistic Distribution: Properties and Inference

Castellares, Fredy; Santos, Marcos A. C.; Montenegro, Lourdes C.; Cordeiro, Gauss M.

doi:10.1080/01966324.2014.954296

Cited by 8 publications

(7 citation statements)

References 15 publications

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“…Particular gamma G I distributions studied in the literature include the gamma Dagum distribution (Oluyede, Huang, and Pararai 2014), the gamma exponentiated Weibull distribution (Castellares and Lemonte 2015), the gamma extended Frechet distribution (Silva, Andrade, Maciel, Campos, and Cordeiro 2013), the gamma half normal distribution (Alzaatreh and Knight 2013), the gamma inverse Weibull distribution (Pararai, Warahena-Liyanage, and Oluyede 2014), the gamma linear failure rate distribution (Cordeiro, Ortega, and Popovic 2014a), the gamma log-logistic distribution (Ramos, Cordeiro, Marinho, Dias, and Hamedani 2013), the gamma logistic distribution (Castellares, Santos, Montenegro, and Cordeiro 2015), the gamma Lomax distribution (Cordeiro, Ortega, and Popovic 2015) and the gamma normal distribution (Alzaatreh, Famoye, and Lee 2014).…”

Section: Families Of Distributions and R Codementioning

confidence: 99%

Newdistns: AnRPackage for New Families of Distributions

Nadarajah

Rocha²

2016

J. Stat. Soft.

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The contributed R package Newdistns written by the authors is introduced. This package computes the probability density function, cumulative distribution function, quantile function, random numbers and some measures of inference for nineteen families of distributions. Each family is flexible enough to encompass a large number of structures. The use of the package is illustrated using a real data set. Also robustness of random number generation is checked by simulation.

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Section: Families Of Distributions and R Codementioning

confidence: 99%

Newdistns: AnRPackage for New Families of Distributions

Nadarajah

Rocha²

2016

J. Stat. Soft.

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“…There is mounting scientific evidence regarding the inconsistency and weakness of the logit and probit models for skewed binary response data. Recent studies have proposed alternative methods for handling binomial responses, such as: a gamma generated logistic distribution [ 6 ], gamma and log-normal distributions [ 7 ], improved analysis for skewed continuous responses [ 8 ], a skewed Weibull regression model [ 9 ], a generalized logistic distribution [ 10 ], and a skewed logit model [ 4 ]. This shows that modeling non-normality continues to be a topic of importance in recent general research.…”

Section: Introductionmentioning

confidence: 99%

Skewed logit model for analyzing correlated infant morbidity data

et al. 2021

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Background Infant morbidity is a topic of interest because it is used globally as an indicator of the status of health care in a country. A large body of evidence supports an association between bacterial vaginosis (BV) and infant morbidity. When estimating the relationship between the predictors and the estimated variable of morbidity severity, the latter exhibits imbalanced data, which means that violation of symmetry is expected. Two competing methods of analysis, that is, (1) probit and (2) logit techniques, can be considered in this context and have been applied to model such outcomes. However, these models may yield inconsistent results. While non-normal modeling approaches have been embraced in the recent past, the skewed logit model has been given little attention. In this study, we exemplify its usefulness in analyzing imbalanced longitudinal responses data. Methodology While numerous non-normal methods for modeling binomial responses are well established, there is a need for comparison studies to assess their usefulness in different scenarios, especially under a longitudinal setting. This is addressed in this study. We use a dataset from Kenya about infants born to human immunodeficiency virus (HIV) positive mothers, who are also screened for BV. We aimed to investigate the effect of BV on infant morbidity across time. We derived a score for morbidity incidences depending on illnesses reported during the month of reference. By adjusting for the mother’s BV status, the child’s HIV status, sex, feeding status, and weight for age, we estimated the standard binary logit and skewed logit models, both using Generalized Estimating Equations. Results Results show that accounting for skewness in imbalanced binary data can show associations between variables in line with expectations documented by the literature. In addition, an in-depth analysis accounting for skewness has shown that, over time, maternal BV is associated with multiple health conditions in infants. Interpretation Maternal BV status was positively associated with infant morbidity incidences, which highlights the need for early intervention in cases of HIV-infected pregnant women.

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“…There is mounting scientific evidence regarding the inconsistency of the logistic distribution for binary response data. Recent studies have proposed alternative methods for handling binomial responses: assuming a gamma generated logistic distribution [4], gamma and log-normal distributions [5], improved analysis for skewed continuous responses [6], skewed Weibull regression model [7], generalized logistic distribution [8], and skewed logit [3]. This application shows that modeling non-normality continues to be appreciated in recent research; however, few methods have been considered and applied in health research.…”

Section: Introductionmentioning

confidence: 99%

Time effects of bacterial vaginosis on infant morbidities in Kenya assessed using modified skewed generalized estimating equations

Mwenda¹,

Nduati²,

Kosgey³

et al. 2020

Preprint

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Infant morbidity and mortality are indicators used globally as measures of a country’s health status. Among the 8 millennium development goals (MDGs), this study aimed to address goal four (MDG 4) on the reduction of child mortality and six (MDG 6) on combating HIV and other diseases. We assessed different health conditions caused by bacterial vaginosis (BV) that could have life-long effects among infants. We aimed to address the time effects of BV on the long-term cause of infants' morbidities when asymmetry is assumed. We analyzed infant data from HIV-positive mothers with known BV status from a randomized controlled trial study conducted in Nairobi, Kenya. We aimed to investigate the effect of BV on infant morbidity with time from birth up to the age of 6 months. We derived a score for morbidity incidences depending on illnesses reported in the register during scheduled visits only. By adjusting for the mother’s BV status, child’s HIV status, sex, feeding status, and weight for age, we used two approaches for analysis. We considered and fitted the traditional generalized estimating (GEE) equations and our proposed skewed generalized estimating equations (SGEE). Overall, we included information on 327 infants. One thousand nine hundred sixty-two repeated measurements were available for analysis. Among the 327 mothers, 148 (45%) tested positive for BV, while 179 (55%) tested negative. We found that BV, gender, and time were associated with multiple health conditions in infants. Infants of women who tested positive for BV, at month 1, had 4.46 higher odds of various health conditions compared to infants of mothers who tested negative. The effects of BV tended to decrease with time, and at 5 months of age, children in the BV group had 1.10 times the odds of experiencing morbidity incidence. In the SGEE model, BV was statistically significant at the 0.05 level with a positive coefficient, indicating that children in the BV group had a higher probability of experiencing multiple morbidities. BV is a significant predictor of infant morbidity because its effects on exposed infants could persist over time. In contrast, the traditional GEE results showed an insignificant positive coefficient. The results indicate the need to factor in the skewness during analysis in case of data transformation, especially when converting from continuous to binary data for parsimony and straightforward interpretation of the effects of covariates. Maternal BV status was positively associated with morbidity incidences, which highlights the need for early intervention for infected women. Accelerated programs promoting access to BV treatment with proper infant handling practices that better deal with emerging multiple health conditions in infants may prove useful in reducing the incidence of infant morbidity in Kenya. Emphasis on care to promote better health for infants during growth is necessary to achieve the MDGs.

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A Gamma-Generated Logistic Distribution: Properties and Inference

Cited by 8 publications

References 15 publications

Newdistns: AnRPackage for New Families of Distributions

Newdistns: AnRPackage for New Families of Distributions

Skewed logit model for analyzing correlated infant morbidity data

Time effects of bacterial vaginosis on infant morbidities in Kenya assessed using modified skewed generalized estimating equations

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