scholarly journals Simultaneous minimax estimation of parameters of multinomial distribution

2002 ◽  
Vol 29 (3) ◽  
pp. 307-311
Author(s):  
Stanisław Trybuła
Keyword(s):  
Multinomial Distribution ◽  
Minimax Estimation ◽  
Estimation Of Parameters

scholarly journals Variaciones espaciales y ontogenéticas en la dieta de un plecóptero de amplia distribución Claudioperla tigrina Klapálek (Plecoptera: Gripopterygidae)

2017 ◽  
Vol 65 (3) ◽  
pp. 1174
Author(s):  
María Celina Reynaga ◽  
Natalia Dávalos ◽  
Carlos Molineri
Keyword(s):  
Organic Matter ◽  
Food Item ◽  
Dietary Habits ◽  
Developmental Stages ◽  
Multinomial Distribution ◽  
Estimation Of Parameters ◽  
Ecological Processes ◽  
Size Classes ◽  
Positive Side ◽  
Definition Of

Dietary information gives insight into several ecological processes acting in lotic ecosystems. This work aimed: 1) to identify the dietary habits of Claudioperla tigrina immature stages along a wide altitudinal as well as latitudinal gradient in North Argentina; 2) to define the functional feeding group (FFG) of C. tigrina; 3) to evaluate differences in diet in the studied sites. Studied nymphs were collected from localities widely scattered in Northwestern Argentina and they fell into different developmental stages (four size classes). The ingested material was extracted from the foregut and midgut by using thorax ventral dissection. Dietary profiles were analyzed through the estimation of parameters associated with a Dirichlet-multinomial distribution. ANOVA’s were performed for each food item using sites as factor. Multidimensional Scaling was used to identify sites with similar dietary profiles. An analysis of food-niche breadth was also performed to evaluate the degree of dietary diversification for the resources consumed in each site. Mouthparts are similar across the different size classes, excepting the increasing sclerotization recorded with age. Mouthparts retained most of the typical chewing groundplan, showing relatively short labial and maxillar palps, and strong, sclerotized and denticulated mandibles and maxillae. Our results pointed out that the nymphs of C. tigrina always ingest two or more food items (CPOM, FPOM, invertebrates and algae), suggesting thus a flexible diet. The diet changed in relation to body size, while finer particles were consumed in the early stages, larger particles were ingested in final stages. Coarse particulate organic matter was the dominant food item, with signals of shredding during ingestion. Differences between sites for FPOM, invertebrates, algae and sediment were detected, but not for MOPG. Correlations were obtained for the first two axis of the MDS analysis. Sites AP, LT, LI, C and M (Yungas Rainforest and Humid Grassland) were negatively correlated with the axis 1 which was associated with increased consumption of FPOM. On the positive side of the axis the site P (High Andes) is associated with a greater proportion of invertebrates and sediment. The sites IN (Humid Grassland) and LR (Argentine Northwest Monte and Thistle of the Prepuna) were located at the positive domain of axis 2 which is in turn associated with a greater count of algae in the dietary contents. We found significant differences in the quantity of secondary items, and this is likely related with the resources environmental availability. The FFG of Claudioperla tigrina is primarily shredder/collector-gatherer in Yungas Rainforest and Humid Grassland shredder/predator in High Andes. FFG classification of C. tigrina and the definition of their role for organic matter processing is an important step for future studies based on functional groups such as analysis of food webs.

scholarly journals Use of the Multinomial Dirichlet Model for Analysis of Subdivided Genetic Populations

Genetics ◽  
1987 ◽  
Vol 115 (2) ◽  
pp. 363-366
Author(s):  
C J Jiang ◽  
C Clark Cockerham
Keyword(s):  
Dirichlet Distribution ◽  
Multinomial Distribution ◽  
Estimation Procedure ◽  
Estimation Of Parameters ◽  
Drift Model ◽  
Distribution Estimation ◽  
Compound Distribution ◽  
Subdivided Populations ◽  
Dirichlet Model

ABSTRACT The distribution found by compounding the multinomial distribution with the Dirichlet distribution has been suggested as a basis for the estimation of parameters in subdivided populations, in particular of the "correlation between genotypes" within subpopulations. It is shown that the estimators deriving from these procedures perform poorly when the data are generated by the classical Wright drift model of subdivided populations. This conclusion suggests that the compound distribution estimation approach does not provide a good estimation procedure for real populations which are reasonably described by the Wright model.

Γ-minimax estimation with delayed observations from the multinomial distribution

Statistics ◽  
2004 ◽  
Vol 38 (3) ◽  
pp. 195-206
Author(s):  
Alicja Jokiel-Rokita ◽  
Ryszard Magiera
Keyword(s):  
Multinomial Distribution ◽  
Minimax Estimation
Sign in / Sign up

Export Citation Format

Share Document