Further notes on the application of zero-inflated models in highway safety

Lord, Dominique; Washington, Simon; Ivan, John N.

doi:10.1016/j.aap.2006.06.004

Cited by 194 publications

(84 citation statements)

References 18 publications

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“…These models represent an alternative way to handle data characterized by a significant amount of zeros or more zeros than the one would expect in a traditional Poisson or NB (Carson and Mannering, 2001;Lee and Mannering, 2002;Qin et al, 2005). However, Lord et al (2005Lord et al ( , 2007 have questioned the validity of these models in most safety modelling circumstances.…”

Section: Models To Evaluate the Influence Of Certain Variables On Roamentioning

confidence: 99%

The influence of economic incentives linked to road safety indicators on accidents: The case of toll concessions in Spain

Rangel

Vassallo

Herraiz

2013

Accident Analysis & Prevention

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The goal of this paper is to evaluate whether the incentives incorporated in toll highway concession contracts in order to encourage private operators to adopt measures to reduce accidents are actually effective at improving safety. To this end, we implemented negative binomial regression models using information about highway characteristics and accident data from toll highway concessions in Spain from 2007 to 2009. Our results show that even though road safety is highly influenced by variables that are not managed by the contractor, such as the annual average daily traffic (AADT), the percentage of heavy vehicles on the highway, number of lanes, number of intersections and average speed; the implementation of these incentives has a positive influence on the reduction of accidents and injuries. Consequently, this measure seems to be an effective way of improving safety performance in road networks.

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Section: Models To Evaluate the Influence Of Certain Variables On Roamentioning

confidence: 99%

The influence of economic incentives linked to road safety indicators on accidents: The case of toll concessions in Spain

Rangel

Vassallo

Herraiz

2013

Accident Analysis & Prevention

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“…The distribution of the observed wean-to-first service interval was over-dispersed (Lord et al 2007), because most sows were inseminated within five days after weaning. Therefore, data were initially recoded so that intervals up to five days, representing sows with a normal weaning-to-first service interval, were designated with zero.…”

Section: Discussionmentioning

confidence: 99%

Effect of sow diets supplementation with chelated trace minerals on their reproductive performance

Skampardonis¹,

Lisgara²,

Papatsiros

et al. 2018

J Hellenic Vet Med Soc

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ABSTRACT. Trace minerals are constituents of proteins and enzymes that are involved in a variety of metabolic processes, having functional implications in growth, development, reproduction and health. Chelated minerals, are minerals bound to organic ligands, usually amino acids, providing higher levels of bioavailability compared to conventional inorganic mineral sources. In the present study, we investigated the effect of partial substitution of inorganic mineral sources with chelated minerals in sows' diets, on three important reproductive parameters, the number of liveborn and weaned piglets and the wean-to-first service interval, in three Greek farrow-to-finish herds. Before initiation of the study the sows were on diets supplemented with 15 mg/kg feed Cu (from CuSO4), 125 mg/kg Zn (from ZnO) and 40 mg/kg Mn (from MnO). After exiting the farrowing facilities they were offered diets in which 93.3%, 36.0% and 62.5% of the supplemented Cu, Zn and Mn, respectively, originated from commercially available chelated minerals. For the last farrowing on inorganic minerals diet and the subsequent one or two (for 35.0% and 65.0% of the studied sows, respectively) on chelated minerals, each sow's reproductive data (total number of parities, number of liveborn and weaned piglets and wean-to-first service interval) were recorded. The reproductive parameters, before and after the supplementation with chelated minerals, were compared in two mixed-effect linear regression models, for the number of liveborn and weaned piglets, and in a zero inflated negative binomial model for the weaning-to-first service interval. There was an improvement of the mean number of liveborn piglets after partial substitution of inorganic source of minerals with chelated minerals by almost half a piglet (P=0.015), whereas there was no effect on the total number of weaned piglets (P=0.15) and the wean-to-first service interval (P=0.65). The increase in the number of liveborn piglets may be directly attributed to improved embryo survival due to increased bioavailability of the organic minerals or indirectly to the beneficial effect of chelated minerals on sows' hoof health, locomotor ability, feed intake and body condition.

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“…However, the distribution of the observed days of wean-tofirst service was over-dispersed (Lord et al 2007). This was expected because most sows were inseminated within five days after weaning.…”

Section: Methodsmentioning

confidence: 99%

Associations between claw lesions and reproductive performance of sows in three Greek herds

Lisgara¹,

Skampardonis²,

Angelidou³

et al. 2015

Vet. Med. - Czech

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ABSTRACT:Claw lesions, which are nowadays very common in sows, are associated with a high risk of early culling and compromised welfare. In this study, we investigated the associations between the severity of claw lesions and three of the most important reproductive indicators, the number of live-born and weaned piglets and the wean-to-first service interval in three Greek farrow-to-finish herds. All studied sows were individually housed during their previous gestations. Sows were examined for lesions, which were scored on a severity scale, on several anatomical sites of the claws, before farrowing. Data on the examined reproductive indicators were retrieved from productivity databases of the herds. Because scoring of lesions on several claw sites resulted in many correlated variables for each sow examined, we employed factor analysis to create a smaller set of uncorrelated variables (factors) which contained all the information in the original variables and produced the corresponding factor scores. The number of live-born and weaned piglets was associated with the produced factor scores in two multivariable linear regression models, whereas the possible associations between the wean-to-first service interval and the factor scores was modelled with the use of zero-inflated negative binomial regression. The number of live-born piglets was negatively associated with factor scores representing lesions on heel (P ≤ 0.001) and sole of front feet (P = 0.019). The number of weaned piglets was also negatively associated with factor scores representing lesions on heel (P = 0.003) of any foot, on sole of front feet (P = 0.001) and on white line, sole and wall of rear feet (P = 0.008), while the wean-to-first service interval was associated with factor scores representing lesions on heel of any foot (P = 0.02), on sole of front feet (P = 0.02) and of dew claw length of front feet (P = 0.009). Our results indicate that combinations of lesions on the dorsal and ventral part of the claws, negatively affected the reproduction parameters considered, emphasising the importance of general improvement of feet health.

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Further notes on the application of zero-inflated models in highway safety

Cited by 194 publications

References 18 publications

The influence of economic incentives linked to road safety indicators on accidents: The case of toll concessions in Spain

The influence of economic incentives linked to road safety indicators on accidents: The case of toll concessions in Spain

Effect of sow diets supplementation with chelated trace minerals on their reproductive performance

Associations between claw lesions and reproductive performance of sows in three Greek herds

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