![[Member-Image]](../assets/img/staff/1-pushpa.webp)
Head, Dept. Stat & Computer Science, Uni. of Peradeniya, Sri Lanka- 
Multivariate Rectangular Confidence Regions
A life member of the Institute of Applied Statistics, Sri Lanka
Member - The International Society for Business and Industrial Statistics (http://www.isbis-isi.org/)
DAAD Scholarship for Postgraduate studies - 1987
Life member - SLAASCeylon Journal of Science
SMM Lakmali, LS Nawarathna, P Wijekoon (2022). Bayesian linear regression model for method comparison studies. Ceylon Journal of Science, Vol. 51(1): 37-42.
DOI: http://doi.org/10.4038/cjs.v51i1.7977
Communications in Statistics-Simulation and Computation, Taylor & Francis
Ramajeyam Tharshan, Pushpakanthie Wijekoon (2022). Poisson-Modification of Quasi Lindley regression model for over-dispersed count responses. Communications in Statistics-Simulation and Computation, Taylor & Francis, Published online: 28 Feb 2022.
DOI: https://doi.org/10.1080/03610918.2022.2044052
Faculty of Science, University of Ruhuna, Matara, Sri Lanka
GJMSR Jayasinghe, EPSK Ediriweera, T Wiegand, P Wijekoon (2022). Aggregated adult-recruit spatial pattern of Shorea species explained by dispersal limitation process. Faculty of Science, University of Ruhuna, Matara, Sri Lanka, 2022/1/19.
http://ir.lib.ruh.ac.lk/xmlui/handle/iruor/5541
Reliability: Theory & Applications
Ramajeyam Tharshan, Pushpakanthie Wijekoon (2022). A New Mixed Poisson Distribution for Over-dispersed Count Data: Theory and Applications. Reliability: Theory & Applications, 17(1): 33-51.
DOI: https://doi.org/10.24412/1932-2321-2022-167-33-51
Ceylon Journal of Science
Tharshan, R., & Wijekoon, P. (2022). Performance of various sub-models of a new Lindley family of distributions: A comparative study based on the simulated data sets. Ceylon Journal of Science, 51(2): 111–120.
DOI: http://doi.org/10.4038/cjs.v51i2.8005
Communications in Statistics - Simulation and Computation
Ramajeyam Tharshan and Pushpakanthie Wijekoon (2022). Ridge estimator in a mixed Poisson regression model. Communications in Statistics - Simulation and Computation, Online version.
DOI: https://doi.org/10.1080/03610918.2022.2101064
Scientific World Journal, Hindawi
Ramajeyam Tgarshan and Pushpakanthie Wijekoon (2022). On a Mixed Poisson Liu Regression Estimator for Overdispersed and Multicollinear Count Data. Scientific World Journal, Hindawi, Volume 2022, Article ID 8171461: 18 pages.
DOI: https://doi.org/10.1155/2022/8171461
Journal of the University of Ruhuna
Manickavasagar Kayanan and Pushpakanthie Wijekoon (2022). Generalized Stochastic Restricted LARS Algorithm. Journal of the University of Ruhuna, Vol.13(1): 14-28.
DOI: http://doi.org/10.4038/rjs.v13i1.112
Journal of the University of Ruhuna
S. M. J. H. Nisansala, P. Wijekoon (2022). Identifying Extreme Behaviour and Fitting Empirical Models for Dengue Incidents of Selected Regions in Sri Lanka. Journal of the University of Ruhuna, 9(2): 72-85.
DOI: http://doi.org/10.4038/jur.v9i2.7977
Statistics in Transition New Series
R Tharshan, P Wijekoon (2022). Zero-modified Poisson-Modification of Quasi Lindley distribution and its application. Statistics in Transition New Series, 23(4): 113-128.
DOI: https://sciendo.com/article/10.2478/stattrans-2022-0045
Communications in Statistics-Simulation and Computation
Nagarajah Varathan, Pushpakanthie Wijekoon (2021). Modified almost unbiased Liu estimator in logistic regression. Communications in Statistics-Simulation and Computation, Vol. 50(11): 3530-3546.
DOI: https://doi.org/10.1080/03610918.2019.1626888
arXiv preprint arXiv:2110.13004
Ramajeyam Tharshan, Pushpakanthie Wijekoon (2021). Poisson-modification of the Quasi Lindley distribution and its zero modification for over-dispersed count data. arXiv preprint arXiv:2110.13004, .
DOI: https://arxiv.org/abs/2110.13004
Statistical Papers
Nagarajah Varathan, Pushpakanthie Wijekoon (2021). Optimal stochastic restricted logistic estimator. Statistical Papers, Vol. 62(2): 985-1002.
DOI: https://doi.org/10.1007/s00362-019-01121-y
Open Journal of Statistics
Ramajeyam Tharshan, Pushpakanthie Wijekoon (2021). A Modification of the Quasi Lindley Distribution. Open Journal of Statistics, Vol. 11: 369-392.
DOI: https://doi.org/10.4236/ojs.2021.113022
Proceedings of PGIS Research Congress 2021
Tharshan, R. and Wijekoon, P. (2021). Adoption of Ridge Estimator in Poisson Modification of Quasi Lindley Regression Model to overcome multicollinearity. Proceedings of PGIS Research Congress 2021, : 47.
Proceedings of Peradeniya University International Research Sessions 2021
S.U. Adikaram, T.K.S. Priyangani, M. Senarathna, P. Wijekoon, G. Bowatte, X. Chen and R. Weerasooriya (2021). Geostatistical Method for Compilation of Spatial TDS Variations in Groundwater. Proceedings of Peradeniya University International Research Sessions 2021, : 128.
Proceedings of Peradeniya University International Research Sessions 2021
S.M.M. Lakmali, L.S. Nawarathna and P. Wijekoon (2021). Bayesian Model for Heteroscedastic Measurements in Method Comparison Data. Proceedings of Peradeniya University International Research Sessions 2021, : 498.
Proceedings of Peradeniya University International Research Sessions 2021
P. Priyadarshana and P. Wijekoon (2021). Analysing Leptospirosis Incidence and Its Association with Climatic Factors in Sri Lanka. Proceedings of Peradeniya University International Research Sessions 2021, : 501.
Proceedings of Peradeniya University International Research Sessions 2021
D. Dissanayake, P. Wijekoon, E.P.S.K. Ediriweera3 and I.A.U.N. Gunatilleke (2021). Analysis of Mortality Rates of Plant Species in Sinharaja Forest Dynamics Plot, Sri Lanka, . Proceedings of Peradeniya University International Research Sessions 2021, : 511.
5th International Research Conference of Uva Wellassa University, IRCUWU2021
G.J.M.S.R. Jayasinghe, P. Wijekoon, T. Wiegand and E.P.S.K. Ediriweera (2021). Adult-Recruit Spatial Association of Shorea Species Determined by Topographic Variation in a Mixed-Dipterocarp Tropical Rainforest, Sri Lanka, . 5th International Research Conference of Uva Wellassa University, IRCUWU2021, : 171.
Journal of Probability and Statistics, Hindawi
Manickavasagar Kayanan and Pushpakanthie Wijekoon (2020). Stochastic Restricted LASSO-Type Estimator in the Linear Regression Model. Journal of Probability and Statistics, Hindawi, 2020: 7 pages.
DOI: https://doi.org/10.1155/2020/7352097
Open Journal of Statistics
Manickavasagar Kayanan and Pushpakanthie Wijekoon (2020). Variable Selection via Biased Estimators in the Linear Regression Model. Open Journal of Statistics, 10(1): 113-126.
DOI: https://doi.org/10.4236/ojs.2020.101009
Statistics in Transition New Series
Ramajeyam Tharshan and Pushpakanthie Wijekoon (2020). A comparison study on a new five-parameter generalized Lindley distribution with its sub-models. Statistics in Transition New Series, 21(2): 89-117.
DOI: https://doi.org/10.21307/stattrans-2020-015
Open Journal of Statistics
R. Tharshan and P. Wijekoon (2020). Location-Based Generalized Akash Distribution: Properties and Applications. Open Journal of Statistics, 10(2): 163-187.
DOI: https://doi.org/10.4236/ojs.2020.102013
Ecology Letters
Tak Fung, et.al. (2020). Temporal population variability in local forest communities has mixed effects on tree species richness across a latitudinal gradient. Ecology Letters, 23: 160-171.
DOI: https://doi.org/10.1111/ele.13412
Rajarata University Journal
Selvaratnam,
Ahthiga & Pushpakanthie Wijekoon (2020). Fitting a
Poisson-Gamma Model for Rainfall Occurrence and Rainfall Amount in Colombo
District, Sri Lanka. Rajarata University Journal, 5(1): 77-84.
https://www.rjt.ac.lk/contents/?page=225
Proceedings PGIS Research Congress 2020
Tharshan, R. and Wijekoon, P (2020). Performance of various location based Lindley family distributions based on Akaike Information Criterion.. Proceedings PGIS Research Congress 2020, : 52.
Communications in Statistics: Case Studies, Data Analysis and Applications
Manickavasagar Kayanan and Pushpakanthie Wijekoon (2019). Optimal estimators in misspecified linear regression model with an application to real-world data. Communications in Statistics: Case Studies, Data Analysis and Applications, 4(3-4): 151-163.
DOI: https://www.tandfonline.com/doi/full/10.1080/23737484.2018.1536863
Asian Journal of Environment & Ecology
P. M. S. S. Kumari and P. Wijekoon (2019). Distribution of Butterfly Species Associated with Environmental Factors in Sri Lanka. Asian Journal of Environment & Ecology, 9(3): 1-18.
DOI: https://doi.org/10.9734/ajee/2019/v9i330093
Statistical Papers
Nagarajah Varathan and Pushpakanthie Wijekoon (2019). Logistic Liu Estimator under stochastic linear restrictions. Statistical Papers, 60(3): 595-612.
DOI: https://doi.org/10.1007/s00362-016-0856-6
Journal of Open Source Software
Amalan Mahendran and Pushpakanthie Wijekoon (2019). fitODBOD: An R Package to Model Binomial Outcome Data using Binomial Mixture and Alternate Binomial Distributions. Journal of Open Source Software, 4(39),1505: 1-5.
DOI: https://doi.org/10.21105/joss.01505
Communications in Statistics: Case Studies, Data Analysis and Applications
Amali Jayatileke, Lakshika S. Nawarathna, Nalini Ravishanker, P. Wijekoon, Ruwan D. Nawarathna, V. S. N. Vithanaarachchi, R. L.
Wijeyaweera (2019). New standards for eruption time and sequence of permanent dentition in Sri Lankan children. Communications in Statistics: Case Studies, Data Analysis and Applications, 5(2): 92-100.
DOI: https://doi.org/10.1080/23737484.2019.1579075
Statistical Papers, Springer
Nagarajah Varathan, Pushpakanthie Wijekoon (2019). Optimal stochastic restricted logistic estimator. Statistical Papers, Springer, Online First: 1-18.
DOI: https://link.springer.com/article/10.1007/s00362-019-01121-y
Ceylon Journal of Science
M. Kayanan and P. Wijekoon (2019). Performance of LASSO and Elastic net estimators in Misspecified Linear Regression Model. Ceylon Journal of Science, 48(3): 293–299.
DOI: https://doi.org/10.4038/cjs.v48i3.7654
Sankhya B: The Indian Journal of Statistics, Springer
Pushpakanthie Wijekoon, Alwell Oyet and Brajendra C. Sutradhar (2018). Pair-Wise Family-Based Correlation Model for Spatial Count Data. Sankhya B: The Indian Journal of Statistics, Springer, .
DOI: https://doi.org/10.1007/s13571-017-0150-1
Communication in Statistics-Theory and Methods, Taylor & Francis
Nagarajah Varathan, Pushpakanthie Wijekoon (2018). Optimal Generalized Logistic Estimator. Communication in Statistics-Theory and Methods, Taylor & Francis, 47(2): 463-474.
DOI: https://dx.doi.org/10.1080/03610926.2017.1307406
Ceylon Journal of Science
Nagarajah Varathan, Pushpakanthie Wijekoon (2018). Liu-Type logistic estimator under Stochastic Linear Restrictions. Ceylon Journal of Science, 47(1): 21-34.
DOI: https://doi.org/10.4038/cjs.v47i1.7483
Journal of Probability and Statistics, Wiley Hindawi
Kayanan, M. and Wijekoon, P. (2018). Stochastic Restricted Biased Estimators in Misspecified Regression Model with Incomplete Prior Information. Journal of Probability and Statistics, Wiley Hindawi, 2018 article ID 1452181: 8 pages.
DOI: https://doi.org/10.1155/2018/1452181
Cran R project.org (https://cran.r-project.org/web/packages/fitODBOD/index.html)
Amalan Mahendran, Pushpakanthie Wijekoon (2018). R Package: fitODBOD, Modeling Over Dispersed Binomial Outcome Data Using BMD and ABD. Cran R project.org (https://cran.r-project.org/web/packages/fitODBOD/index.html), .
https://amalan-constat.github.io/R-fitODBOD/
Asian Journal of Probability and Statistics
K. A. N. K. Karunarathna and Pushpakanthie Wijekoon (2018). Modeling Count Data from Dependent Clusters with Poisson Mixed Models. Asian Journal of Probability and Statistics, 1(2): 1-21.
DOI: https://doi.org/10.9734/AJPAS /2018/ 41699
Scholars Journal of Applied Medical Sciences
D.A.R.K. Dasanayaka and Pushpakanthie Wijekoon (2018). Reference Values for Spirometry for Healthy Sri Lankan Adults: Age between 20 To 65 Years. Scholars Journal of Applied Medical Sciences, 6(9): 3421-3431.
DOI: https://doi.org/10.21276/sjams.2018.6.9.38
British Journal of Mathematics & Computer Science
DK Ishara, P Wijekoon (2017). Time Series Analysis for Modeling and Forecasting International Tourist Arrivals in Sri Lanka,. British Journal of Mathematics & Computer Science, 20 (5): 1-9.
DOI: https://dx.doi.org/10.9734/BJMCS/2017/31726
Communications in Mathematics and Statistics
Sivarajah Arumairajan, Pushpakanthie Wijekoon (2017). Modified Almost Unbiased Liu Estimator in Linear Regression Model,. Communications in Mathematics and Statistics, 5 (3).
DOI: https://link.springer.com/article/10.1007/s40304-017-0111-z
Statistical Papers
S. Arumairajan, P. Wijekoon (2017). The Generalized preliminary test estimator when different sets of stochastic restrictions are available,. Statistical Papers, 58 (3): 729-747 .
DOI: https://doi.org/10.1007/s00362-015-0723-x
Ceylon Journal of Science
G. J. M. S. R. Jayasinghe, P. Wijekoon, and J. Gunatilake (2017). Landslide susceptibility assessment using statistical models: A case study in Badulla district, Sri Lanka. Ceylon Journal of Science, 46(4): 27-41.
DOI: https://doi.org/10.4038/cjs.v46i4.7466
Open Journal of Statistics
Kayanan, M. and Wijekoon, P. (2017). Performance of Existing Biased Estimators and the Respective Predictors in a Misspecified Linear Regression Model. Open Journal of Statistics, 7(5): 876-900.
DOI: https://doi.org/10.4236/ojs.2017.75062
Communication in Statistics-Theory and Methods
Sivarajah Arumairajan, P Wijekoon (2016). Generalized Preliminary Test Stochastic Restricted Estimator in the Linear Regression Model. Communication in Statistics-Theory and Methods, 45(20): 6061-6086.
DOI: https://dx.doi.org/10.1080/03610926.2014.957850
Open Journal of Statistics
N Varathan, P Wijekoon (2016). On the Restricted Almost Unbiased Ridge Estimator in Logistic Regression,. Open Journal of Statistics, Vol. 6(6): 1076.
DOI: https://doi.org/10.4236/ojs.2016.66087
Statistical Papers, Springer
N Varathan, P Wijekoon (2016). Logistic Liu Estimator under stochastic linear restrictions,. Statistical Papers, Springer, : 1-18.
DOI: https://doi.org/10.1007/s00362-016-0856-6
British Journal of Mathematics & Computer Science
S. G. J. Senarathne and P. Wijekoon (2016). A New Selection Index to Address within Course Competition and between Course Competition for Ranking Examination Scores. British Journal of Mathematics & Computer Science, 13(6): 1-17.
DOI: https://doi.org/10.9734/ BJMCS /201 6 / 23213
British Journal of Mathematics & Computer Science
N Varathan, P Wijekoon (2016). Ridge Estimator in Logistic Regression under Stochastic Linear Restrictions,. British Journal of Mathematics & Computer Science, 15 (3): 1-1411.
DOI: https://doi.org/10.9734/BJMCS/2016/24585
Journal of Modern Applied Statistical Methods
Sivarajah Arumairajan, Pushpakanthie Wijekoon (2016). Principal Component Preliminary Test Estimator in the Linear Regression Model,. Journal of Modern Applied Statistical Methods, Vol 15(1): 690-710.
DOI: https://doi.org/10.22237/jmasm/1462077180
Cran R project.org
Ajith Dissanayake, Pushpakanthie Wijekoon (2016). R Package: lrmest: Different Types of Estimators to Deal with Multicollinearity. Cran R project.org, .
https://cran.r-project.org/web/packages/lrmest/index.htm
Open Journal of Statistics
N Varathan, P Wijekoon (2015). Stochastic restricted maximum likelihood estimator in logistic regression model,. Open Journal of Statistics, Vol. 5(7): 837.
DOI: https://doi.org/10.4236/ojs.2015.57082
Open Journal of Statistics
Sivarajah Arumairajan, Pushpakanthie Wijekoon, (2015). More on the Preliminary Test Stochastic Restricted Liu Estimator in Linear Regression Model,. Open Journal of Statistics, Vol5(4): 340-349.
DOI: https://dx.doi.org/10.4236/ojs.2015.54035
Journal of the National Science Foundation of Sri Lanka
SCD Wimalasena, P Wijekoon, SS Fernando, IAUN Gunatilleke (2015). Application of clustering and ordination methods to determine the optimal plot size for vegetation sampling of a Sri Lankan dipterocarp forest. Journal of the National Science Foundation of Sri Lanka, Vol 43(1): 91-98.
DOI: https://doi.org/10.4038/jnsfsr.v43i1.7919
Open Journal of Statistics
Sivarajah Arumairajan, Pushpakanthie Wijekoon (2015). Optimal Generalized Biased Estimator in Linear Regression Model,. Open Journal of Statistics, Vol. 5(5): 403-411.
DOI: https://dx.doi.org/10.4236/ojs.2015.55042
International Journal of Soft Computing and Enginee ring (IJSCE)
R. R. Nanayakkara, Y. P. R. D. Yapa, P. B. Hevawith ana and P. Wijekoon (2015). Automatic Breast Boundary Segmentation of Mammograms,. International Journal of Soft Computing and Enginee ring (IJSCE), Vol. 5(1): 97-101.
https://www.ijsce.org/attachments/File/v5i1/A2540035115.pdf
Environmental geochemistry and health, Springer Netherlands
Hewa MS Wasana, Dharshani Aluthpatabendi, WMTD Kularatne, Pushpa Wijekoon, Rohan Weerasooriya, Jayasundera Bandara (2015). Drinking water quality and chronic kidney disease of unknown etiology (CKDu): synergic effects of fluoride, cadmium and hardness of water. Environmental geochemistry and health, Springer Netherlands, Vol. 37(2): 221-231.
DOI: https://dx.doi.org/10.1007/s10653-015-9699-7
Statistical Paper-Springer
Arumairajan. S and Wijekoon P. (2015). The Generalized Preliminary Test Estimator when different sets of stochastic restrictions are available. Statistical Paper-Springer, .
DOI: https://dx.doi.org/10.1007/s00362-015-0723-x
Evidence from Sri Lanka, International Journal of Development Research
R. M. I. P. Ratnayake, P. Wijekoon, Yapa. R.D. (2014). Relationship Between All Share Price Index (ASPI) and Macroeconomic Variables. Evidence from Sri Lanka, International Journal of Development Research, Vol.4(9): 1923-1928.
https://www.journalijdr.com/sites/default/files/2117.pdf
British Journal of Mathematics & Computer Science
Sivarajah Arumairajan, Pushpakanthie Wijekoon (2014). Preliminary Test Stochastic restricted r-k Class Estimator and Preliminary Test Stochastic Restricted r-d Class Estimator in Linear Regression Model,. British Journal of Mathematics & Computer Science, 5(2): 204-227.
DOI: https://dx.doi.org/10.9734/BJMCS/2015/13781
Journal of Statistical and Econometric Methods
Sivarajah Arumairajan, Pushpakanthie Wijekoon (2014). Improvement of Ridge Estimator When Stochastic Restrictions Are Available in the Linear Regression Model,. Journal of Statistical and Econometric Methods, vol.3, no.1: 35-48.
https://dlib.pdn.ac.lk/bitstream/1/4539/1/JOSEM%20second%20paper.pdf
Open Journal of Statistics
Sivarajah Arumairajan, Pushpakanthie Wijekoon (2013). Improvement of the Preliminary Test Estimator When Stochastic Restrictions are Available in Linear Regression Model,. Open Journal of Statistics, Vol. 3: 283-292 (Scientific Research Publishing Inc ).
DOI: https://dx.doi.org/10.4236/ojs.2013.34033
International Journal of Statistics and Probability
Chandrabose Manoj, Pushpa Wijekoon and Roshan D. Yapa (2013). The McDonald Generalized Beta-Binomial Distribution: A New Binomial Mixture Distribution and Simulation Based Comparison with Its Nested Distributions in Handling Overdispersion,. International Journal of Statistics and Probability, Vol. 2, No. 2; ISSN 1927-7032 E-ISSN 1927-7040: Published by Canadian Center of Science and Educat.
DOI: https://dx.doi.org/10.5539/ijsp.v2n2p24
Statistics in Action -International Workshop
Chandrabose Manoj, Pushpa Wijekoon and Roshan D. Yapa (2013). Recent Advances of Binomial Mixture Models in Ecological Applications, Proceeding of:. Statistics in Action -International Workshop, India.
Conference on Sri Lanka - Japan Collaborative Research 2013
Chandrabose Manoj, Pushpa Wijekoon and Darshana. Yapa (2013). An Improved Method of Modelling Plant Species Population in Japanese Grasslands Using a Generalized Beta-Binomial Distribution, Proceeding of. Conference on Sri Lanka - Japan Collaborative Research 2013, Sri Lanka.
International Conference: Statistics, Science, and Society
Chandrabose Manoj, Pushpa Wijekoon (2013). A Simulation based comparison of Binomial Mixture Distributions in handling overdispersion,. International Conference: Statistics, Science, and Society, New Challenges and Opportunities: Chennai, India .
Monograph Series, Institute of Applied Statistics, Sri Lanka, ISSN 2345-9883
Pushpakanthie Wijekoon (2013). Cluster Analysis Using R. Monograph Series, Institute of Applied Statistics, Sri Lanka, ISSN 2345-9883, .
https://www.youblisher.com/p/1816583-CLUSTER-ANALYSIS-USING-R/
Lab Manual, PGIS Short Course
P. Wijekoon, R.D. Yapa, Manoj Bose (2013). Short Course on Data Analysis using R, RStudio and RCommander. Lab Manual, PGIS Short Course, .
https://www.youblisher.com/p/1874333-Short-Course-notes-for-Data-analysis/
Statistical papers, Springer
Laheetharan A. and P. Wijekoon (2011). Mean square error comparison among variance estimators with known coefficient of variation. Statistical papers, Springer, 47: 471-479.
DOI: https://dx.doi.org/10.1007/s00362-009-0221-0
Statistical papers, Springer
Laheetharan A. and P. Wijekoon (2010). Improved estimation of the population parameters when some additional information is available. Statistical papers, Springer, 51: 889-914.
DOI: https://dx.doi.org/10.1007/s00362-008-0185-5
K. A. N. K. Karunarathna, P. Wijekoon, K. B. Ranawana (2010). Abundance pattern of land snails in Knuckles forest, Peradeniya University Research sessions, Vol 15-PartII, 543-546 . , .
Peradeniya University Research sessions
D.M.C.K. Dissanayake, P. Wijekoon and Jagath Gunatilake (2010). Spatial distribution of Groundwater Geochemistry in Wariyapola area,. Peradeniya University Research sessions, Vol 15-PartII: 528-531 .
Peradeniya University Research sessions
R.P.Senadeera and P. Wijekoon (2010). Modelling distributions and forecasting of wind speed in selected whether stations of Sri Lanka,. Peradeniya University Research sessions, Vol 15-PartII: 531-534 .
Peradeniya University Research sessions
H.H.Y.De Silva, P. Wijekoon and I.A.U.N.Gunatilleke (2010). Identifying the flowering patterns of Phenological events of eight Shorea species in Sri Lanka,. Peradeniya University Research sessions, Vol 15-PartI: 290-293 .
Peradeniya University Research sessions
C.Manoj, P. Wijekoon, Roshan D. Yapa (2010). Adjustment on William’s method when negative variance components occur in underdispersed Logistic models,. Peradeniya University Research sessions, Vol 15-PartII: 759-762 .
The Sri Lankan Journal of Applied Statistics
Laheetharan A. and P. Wijekoon (2009). Optimal combined estimators for population parameters with known prior information,. The Sri Lankan Journal of Applied Statistics, Vol 10: 137 – 152 .
Sri Lankan Journal of Applied Statistics
Laheetharan A. and P. Wijekoon (2009). Estimation of variance in Inverse Gaussian distribution with known kurtosis,. Sri Lankan Journal of Applied Statistics, Vol. 9: 84-92 .
Peradeniya University Research sessions
C.Manoj, P. Wijekoon, Roshan D. Yapa (2009). Patterns of Density plots of Random Effects Logistic Regression Models,. Peradeniya University Research sessions, Vol 14-PartII: 577-580 .
Peradeniya University Research sessions
C. Paranirupanathan, P. Wijekoon (2009). A Study of Inflation in Sri Lanka using new Colombo Consumer’s Price Index (CCPI(N)) with compared to the old CCPI,. Peradeniya University Research sessions, Vol 14-PartII: 580-583 48.
Peradeniya University Research sessions
A.S. Kalpage, P. Wijekoon and S. Madawala (2009). Spatial Distribution of soil nutrients in the Forest Dynamic plot in Sinharaja,. Peradeniya University Research sessions, Vol 14-PartII: 583-586 .
Peradeniya University Research sessions
W.L.R.D.Gunathilaka, P. Wijekoon, K.M.G.G. Jayasuriya (2009). , Effects of Storage Temperature and Storage time on Physical Dormancy break of Ipomeoa Hederacea seeds,. Peradeniya University Research sessions, Vol 14-PartII: 586-589 .
Peradeniya University Research sessions
P.M.S.A. Ruwan, P. Wijekoon and S. Madawala (2009). Statistical Model based solution on identifying negative factors in Forest colonization,. Peradeniya University Research sessions, Vol 14-PartII: 580-583 .
Peradeniya University Research sessions
Laheetharan A. and P. Wijekoon (2008). “Estimating the population variance of binomial distribution when kurtosis is known”,. Peradeniya University Research sessions, Vol 13-PartII: 366-369 .
Peradeniya University Research sessions
D. Edirisinghe, P. Wijekoon and L. Perera (2008). “A study of the influence of school and home environments on the health of children”,. Peradeniya University Research sessions, Vol 13-PartII: 369-372 .
Peradeniya University Research sessions
Laheetharan A. and P. Wijekoon (2008). “Estimating the population variance of binomial distribution when kurtosis is known”,. Peradeniya University Research sessions, Vol 13-PartII: 366-369 .
Peradeniya University Research sessions
P.M.S.A. Ruwan, P. Wijekoon and D.R. Weerasekara (2008). “A study on interviewer effect on multi-stage sample surveys”,. Peradeniya University Research sessions, Vol 13-PartII: 362-366 .
Peradeniya University Research sessions
C.L. jayasinghe, P. Wijekoon and P.V.R. Kumarasiri (2008). “A study on related factors of alcohol and tobacco among school children in Anuradhapura district”,. Peradeniya University Research sessions, Vol 13-PartII: 359-362 .
Statistical Papers
Hubert M.H. and P. Wijekoon (2006). Improvement of the Liu estimator in Linear Regression model. Statistical Papers, 47: 471-479.
DOI: https://dx.doi.org/10.1007/s00362-006-0300-4
Ceylon Journal of Science : Physical Sciences
Hubert M.H. and P. Wijekoon (2005). Efficiency of the Stochastic restricted Liu estimator on incomplete data regression model. Ceylon Journal of Science : Physical Sciences, 10: 39-45 .
Statistical papers, Springer
E Wencheko and P. Wijekoon (2005). Improved estimation of the mean in one-parameter exponential families with known coefficient of variation. Statistical papers, Springer, Vol 46: 101-115.
DOI: https://dx.doi.org/10.1007/BF02762037
International Sri Lankan Statistical Conference
P. Wijekoon and Hubert M.H. (2004). Modified Liu Estimator with Incomplete Prior Information in Misspecified Regression Model, Proceedings of the. International Sri Lankan Statistical Conference, Visions of Futuristic Statistical Methodologies: 533-546.
DOI: https://dx.doi.org/10.13140/2.1.1963.4888
International Sri Lankan Statistical Conference
Hubert M.H. and P. Wijekoon (2004). Comparisons between Stochastic Restricted Liu Estimators When Different Sets of Prior Information are Available, Proceedings of the. International Sri Lankan Statistical Conference, Visions of Futuristic Statistical Methodologies: 255-262 ..
DOI: https://dx.doi.org/10.13140/2.1.4060.6407
Statistica Anno. LXIV
Hubert M.H. and Pushpa Wijekoon (2004). Superiority of the stochastic restricted Liu estimator under misspecification,. Statistica Anno. LXIV, n.1, 2004: pp. 153-162.
DOI: https://doi.org/10.6092/issn.1973-2201/29
Sri Lankan Journal of Applied Statistics
Jahufer A. and P. Wijekoon (2003). A Monte Carlo Evaluation of new biased estimators in Regression model. Sri Lankan Journal of Applied Statistics, 4: 37-46 .
Ceylon Journal of Science : Physical Sciences
Wijekoon P. (1998). A comparison of the Restricted Ridge Regression and the Modified Ridge Regression estimators. Ceylon Journal of Science : Physical Sciences, 5(I): 75 – 79 .
Ceylon Journal of Science, Physical Sciences
Wijekoon P. and G.Trenkler (1995). Pre-test estimation in the Linear Regression Model under stochastic restrictions. Ceylon Journal of Science, Physical Sciences, 2(I): 57 – 64 .
Communication in Statistics
Dube M., Srivastava V.K., Toutenburg H. and P. Wijekoon (1991). Stein-Rule estimator under inclusion of superfluous variables in Linear Regression Models. Communication in Statistics, 20: 2009-2023.
DOI: https://dx.doi.org/10.1080/03610929108830618
Statistica Anno
Trenkler G. and Pushpa Wijekoon (1989). Mean square error matrix superiority of the mixed regression estimator under misspecification. Statistica Anno, XLIX: 65-71.
DOI: https://doi.org/10.6092/issn.1973-2201/785
Economics Letters
Wijekoon P. and G.Trenkler (1989). Mean square error matrix superiority of estimator under linear restrictions and misspecification. Economics Letters, 30: 141-149.
DOI: https://doi.org/10.1016/0165-1765(89)90052-9