Search results for "GLMM"
showing 6 items of 16 documents
A gradient-based deletion diagnostic measure for generalized linear mixed models
2016
ABSTRACTA gradient-statistic-based diagnostic measure is developed in the context of the generalized linear mixed models. Its performance is assessed by some real examples and simulation studies, in terms of ability in detecting influential data structures and of concordance with the most used influence measures.
The Performance of the Gradient-Like Influence Measure in Generalized Linear Mixed Models
2015
A gradient-like statistic, recently introduced as an influence measure, has been proven to work well in large sample, thanks to its asymptotic properties. In this work, through small-scale simulation schemes, the performance of such a diagnostic measure is further investigated in terms of concordance with the main influence measures used for outlier identification. The simulation studies are performed by using generalized linear mixed models (GLMMs).
Saistība starp briofītu funkcionālajām grupām, substrātu īpašībām un mežau augu sabiedrībām Moricsalas dabas rezervātā
2013
Anotācija Darba mērķis ir noskaidrot substrāta parametru ietekmi uz briofītu sugu bagātību, sugu sastopamību un sugu sadalījumu pa funkcionālajām grupām (dzīves formu un dzīves stratēģiju) dažādās meža augu sabiedrībās, kā arī izpētīt sūnu sugu sastāva mainību Moricsalā pēdējo 100 gadu laikā. Par pētāmo teritoriju izvēlēts Moricsalas dabas rezervātā, kas ir senākā aizsargājamā dabas teritorija Latvijā un ilgstoši neskartās dabas dēļ īpaši piemērota sūnu ekoloģijas izpētei. Pašlaik bagātīgu sūnu sugu sastopamību uz pētītajiem substrātiem nodrošina koku sugas ar atšķirīgu mizas reakciju, dažāda garuma un apkārtmēra kritalas, heterogēns koku sugu sastāvs. Pēdējo 100 gadu laikā Moricsalas meža …
Item Response Trees: a recommended method for analyzing categorical data in behavioral studies
2015
Behavioral data are notable for presenting challenges to their statistical analysis, often due to the difficulties in measuring behavior on a quantitative scale. Instead, a range of qualitative alternative responses is recorded. These can often be understood as the outcome of a sequence of binary decisions. For example, faced by a predator, an individual may decide to flee or stay. If it stays, it may decide to freeze or display a threat and if it displays a threat, it may choose from several alternative forms of display. Here we argue that instead of being analyzed using traditional nonparametric statistics or a series of separate analyses split by response categories, this kind of data ca…
Data from: Predator mimicry, not conspicuousness, explains the efficacy of butterfly eyespots
2015
Large conspicuous eyespots on butterfly wings have been shown to deter predators. This has been traditionally explained by mimicry of vertebrate eyes, but recently the classic eye-mimicry hypothesis has been challenged. It is proposed that the conspicuousness of the eyespot, not mimicry, is what causes aversion due to sensory biases, neophobia or sensory overloads. We conducted an experiment to directly test whether the eye-mimicry or the conspicuousness hypothesis better explain eyespot efficacy. We used great tits (Parus major) as model predator, and tested their reaction towards animated images on a computer display. Birds were tested against images of butterflies without eyespots, with …