Gopalan Nair

University of Western Australia

24Publications

7H-index

235Citations

Publications 24

Newest

#1Greg McSwiggan (UWA: University of Western Australia)H-Index: 1

#2Adrian Baddeley (Curtin University)H-Index: 35

Last.Gopalan Nair (UWA: University of Western Australia)H-Index: 7

view all 3 authors...

Motivated by the study of traffic accidents on a road network, we discuss the estimation of the relative risk, the ratio of rates of occurrence of different types of events occurring on a network of lines. Methods developed for two-dimensional spatial point patterns can be adapted to a linear network, but their requirements and performance are very different on a network. Computation is slow and we introduce new techniques to accelerate it. Intensities (occurrence rates) are estimated by kernel ...

#1Suman Rakshit (Curtin University)H-Index: 3

#2Tilman M. Davies (University of Otago)H-Index: 9

Last.Adrian Baddeley (Curtin University)H-Index: 35

view all 7 authors...

#1Kassel Hingee (UWA: University of Western Australia)H-Index: 1

#2Adrian Baddeley (Curtin University)H-Index: 35

Last.Gopalan Nair (UWA: University of Western Australia)H-Index: 7

view all 4 authors...

We consider a spatial binary coverage map (binary pixel image) which might represent the spatial pattern of the presence and absence of vegetation in a landscape. ‘Lacunarity’ is a generic term for the nature of gaps in the pattern: a popular choice of summary statistic is the ‘gliding-box lacunarity’ (GBL) curve. GBL is potentially useful for quantifying changes in vegetation patterns, but its application is hampered by a lack of interpretability and practical difficulties with missing data. In...

#1Suman Rakshit (Curtin University)H-Index: 3

#2Adrian Baddeley (Curtin University)H-Index: 35

Last.Gopalan NairH-Index: 7

view all 3 authors...

We describe efficient algorithms and open-source code for the second-order statistical analysis of point events on a linear network. Typical summary statistics are adaptations of Ripley's K-function and the pair correlation function to the case of a linear network, with distance measured by the shortest path in the network. Simple implementations consume substantial time and memory. For an efficient implementation, the data structure representing the network must be economical in its use of memo...

Poisson-saddlepoint approximation for gibbs point processes with infinite-order interaction: In memory of Peter Hall

#1Adrian Baddeley (Curtin University)H-Index: 35

#2Gopalan NairH-Index: 7

#1Suman Rakshit (Curtin University)H-Index: 3

#2Gopalan Nair (UWA: University of Western Australia)H-Index: 7

Last.Adrian Baddeley (Curtin University)H-Index: 35

view all 3 authors...

Abstract The analysis of clustering and correlation between points on a linear network, such as traffic accident locations on a street network, depends crucially on how we measure the distance between points. Standard practice is to measure distance by the length of the shortest path. However, this may be inappropriate and even fallacious in some applications. Alternative distance metrics include Euclidean, least-cost, and resistance distances. This paper develops a general framework for the sec...

#1Adrian Baddeley (Curtin University)H-Index: 35

#2Andrew Hardegen (UWA: University of Western Australia)H-Index: 2

Last.Suman Rakshit (Curtin University)H-Index: 3

view all 6 authors...

A major weakness of the classical Monte Carlo test is that it is biased when the null hypothesis is composite. This problem persists even when the number of simulations tends to infinity. A standard remedy is to perform a double bootstrap test involving two stages of Monte Carlo simulation: under suitable conditions, this test is asymptotically exact for any fixed significance level. However, the two-stage test is shown to perform poorly in some common applications: for a given number of simulat...

#1Adrian Baddeley (Curtin University)H-Index: 35

#2Gopalan Nair (UWA: University of Western Australia)H-Index: 7

Last.Gregory Edward McSwiggan (UWA: University of Western Australia)H-Index: 2

view all 4 authors...

#1Gregory Edward McSwiggan (UWA: University of Western Australia)H-Index: 2

#2Adrian Baddeley (Curtin University)H-Index: 35

Last.Gopalan Nair (UWA: University of Western Australia)H-Index: 7

view all 3 authors...

#1Thomas Lawrence (UWA: University of Western Australia)H-Index: 2

#2Adrian Baddeley (Curtin University)H-Index: 35

Last.Gopalan Nair (UWA: University of Western Australia)H-Index: 7

view all 4 authors...

We develop statistical methods for analysing a pattern of points on a region of the sphere, including intensity modelling and estimation, summary functions such as the K function, point process models, and model-fitting techniques. The methods are demonstrated by analysing a dataset giving the sky positions of galaxies. Copyright © 2016 John Wiley & Sons, Ltd.

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