Hybrid copula mixed models for combining case-control and cohort studies in meta-analysis of diagnostic tests

Copula mixed models for trivariate (or bivariate) meta-analysis of diagnostic test accuracy studies accounting (or not) for disease prevalence have been proposed in the biostatistics literature to synthesize information. However, many systematic reviews often include case-control and cohort studies, so one can either focus on the bivariate meta-analysis of the case-control studies or the trivariate meta-analysis of the cohort studies, as only the latter contains information on disease prevalence. In order to remedy this situation of wasting data we propose a hybrid copula mixed model via a combination of the bivariate and trivariate copula mixed model for the data from the case-control studies and cohort studies, respectively. Hence, this hybrid model can account for study design and also due to its generality can deal with dependence in the joint tails. We apply the proposed hybrid copula mixed model to a review of the performance of contemporary diagnostic imaging modalities for detecting metastases in patients with melanoma

The unusual landings of Juveniles of Decapterus russelli and Rastrelliger kanagurta in trawl catches of Veraval

Caputre of fish Juveniles in trawl nets is a common and regular phenomenon ever since the cod end mesh size has been reduced to less than 10 mm. Generally the cod-end catches are a mixture of juveniles of several species of finflshes and shellfishes, along with a host of inedible benthic biota. The occurance of a single species in significantly large quantities is seldom found or reported

Bumper landings of Abalistes stellatus (Lacepede. 1798)

Although trigger fishes are obtained in stray numbers during trawl catches, unusually large specimens are observed in the long trip trawlers operating at 60-100 mts depth. The size ranged from 38 to 43 cm and the catch from 50 to 100 kg/boat. A record landing of about 185.5 tonnes was estimated during the year 2000 at Veraval. The samples collected on 24.11.2000 were identified as the starry triggerfish, Abalistes stellatus (Lacepede, 1798)

Rare record of rainbow runner Elegatis bipinnulata in trawl catches of Veraval

A small quantity of the carangid rainbow runner Elegatis bipinnulata which can easily be mistaken to be a longer mackerel or seer fish was landed on 23.11.2000 at Bhidia trawl landing centre. This species had no scutes on the lateral line, instead had pored scales with rainbow like colour pattern over the body, shape very much resembled to that of Sconiberomoras guttatus

Unusal landings of large-sized Sepia pharaonis from the coastal waters of Saurashtra

Fishing grounds for cuttlefishes are beyond 50m depth zone, off Dwaraka. This report is on unsual landings of Sepia pharaonis from the coastal waters off Saurashtra. The total landing of S. pharaonis was estimated to be around 20 tonnes. It is revealed that minor upwelling has been the reason for this unusual catch

Practice of hooks and line fishery off Satpathi waters, Maharashtra

In trawler boats the fishermen utilize manually operated hooks and line using cephalopods, ribbon fishes, mackerel and other fishes caught in the trawl nets as baits. Trawl nets and hooks and line were employed alternatively and the operation reached a peak in the period from October to January and in the "Mahashivarathri" season. Average catch per boat for the following season (October 1997- January 1998) varied from 200 to 1,000 kg and mainly comprised S.commersoni, Thunnus tonggol and Euthynnus ajfinis along with a few numbers of Epinephelus spp., Rachycentron canadus and P, diacanthus

A vine copula mixed effect model for trivariate meta-analysis of diagnostic test accuracy studies accounting for disease prevalence

A bivariate copula mixed model has been recently proposed to synthesize diagnostic test accuracy studies and it has been shown that it is superior to the standard generalized linear mixed model in this context. Here, we call trivariate vine copulas to extend the bivariate meta-analysis of diagnostic test accuracy studies by accounting for disease prevalence. Our vine copula mixed model includes the trivariate generalized linear mixed model as a special case and can also operate on the original scale of sensitivity, specificity, and disease prevalence. Our general methodology is illustrated by re-analyzing the data of two published meta-analyses. Our study suggests that there can be an improvement on trivariate generalized linear mixed model in fit to data and makes the argument for moving to vine copula random effects models especially because of their richness, including reflection asymmetric tail dependence, and computational feasibility despite their three dimensionality