Publications

2020

  1. Manickavasagar Kayanan and Pushpakanthie Wijekoon; (2020). Stochastic Restricted LASSO-Type Estimator in the Linear Regression Model. Journal of Probability and Statistics, Hindawi.vol. 2020, Article ID 7352097, 7 pages, 2020.
    DOI: https://doi.org/10.1155/2020/7352097

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.
    http://www.rjt.ac.lk/contents/?page=225

2019

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. Nagarajah Varathan, Pushpakanthie Wijekoon; (2019). Optimal stochastic restricted logistic estimator. Statistical Papers, Springer, Online First: 1-18.
    DOI: http://link.springer.com/article/10.1007/s00362-019-01121-y

  7. 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: http://doi.org/10.4038/cjs.v48i3.7654

2018

  1. 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: http://doi.org/10.1007/s13571-017-0150-1

  2. Nagarajah Varathan, Pushpakanthie Wijekoon; (2018). Optimal Generalized Logistic Estimator. Communication in Statistics-Theory and Methods, Taylor & Francis, 47(2): 463-474. DOI: http://dx.doi.org/10.1080/03610926.2017.1307406

  3. Nagarajah Varathan, Pushpakanthie Wijekoon; (2018). Liu-Type logistic estimator under Stochastic Linear Restrictions. Ceylon Journal of Science, 47(1): 21-34. DOI: http://doi.org/10.4038/cjs.v47i1.7483

  4. 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

  5. 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-fitO

  6. 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: http://doi.org/10.9734/AJPAS /2018/41699

  7. 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: http://doi.org/10.21276/sjams.2018.6.9.38

2017

  1. 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: http://dx.doi.org/10.9734/BJMCS/2017/31726

  2. Nagarajah Varathan, Pushpakanthie Wijekoon; (2017). Optimal Generalized Logistic Estimator. Communication in Statistics-Theory and Methods, . DOI: http://dx.doi.org/10.1080/03610926.2017.1307406

  3. 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

  4. 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

  5. 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: http://doi.org/10.4038/cjs.v46i4.7466

  6. Kayanan, M. and P. Wijekoon; (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

2016

  1. 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: http://dx.doi.org/10.1080/03610926.2014.957850

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

2015

  1. 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

  2. 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: http://dx.doi.org/10.4236/ojs.2015.54035

  3. 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: http://doi.org/10.4038/jnsfsr.v43i1.7919

  4. Sivarajah Arumairajan, Pushpakanthie Wijekoon; (2015). Optimal Generalized Biased Estimator in Linear Regression Model,. Open Journal of Statistics, Vol. 5(5): 403-411. DOI: http://dx.doi.org/10.4236/ojs.2015.55042

  5. 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. http://www.ijsce.org/attachments/File/v5i1/A2540035115.pdf

  6. 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: http://dx.doi.org/10.1007/s10653-015-9699-7

  7. Arumairajan. S and P. Wijekoon; (2015). The Generalized Preliminary Test Estimator when different sets of stochastic restrictions are available. Statistical Paper-Springer, DOI: http://dx.doi.org/10.1007/s00362-015-0723-x

2014

  1. 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. http://www.journalijdr.com/sites/default/files/2117.pdf

  2. 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: http://dx.doi.org/10.9734/BJMCS/2015/13781

  3. 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.http://dlib.pdn.ac.lk/bitstream/1/4539/1/JOSEM%20second%20paper.pdf

2013

  1. 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: http://dx.doi.org/10.4236/ojs.2013.34033

  2. 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: http://dx.doi.org/10.5539/ijsp.v2n2p24

  3. 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

  4. 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

  5. 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.

  6. Pushpakanthie Wijekoon; (2013). Cluster Analysis Using R, Monograph Series, Institute of Applied Statistics, Sri Lanka, ISSN 2345-9883 . http://www.youblisher.com/p/1816583-CLUSTER-ANALYSIS-USING-R/

  7. P. Wijekoon, R.D. Yapa and C. Manoj; (2013). Short Course on Data Analysis using R, RStudio and RCommander, Lab Manual, PGIS Short Course http://www.youblisher.com/p/1874333-Short-Course-notes-for-Data-analysis/

2011

  1. 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: http://dx.doi.org/10.1007/s00362-009-0221-0

2010

  1. 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: http://dx.doi.org/10.1007/s00362-008-0185-5

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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.

2009

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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.

2008

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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.

2006

  1. Hubert M.H. and P. Wijekoon; (2006). Improvement of the Liu estimator in Linear Regression model. Statistical Papers, 47: 471-479. DOI: http://dx.doi.org/10.1007/s00362-006-0300-4

2005

  1. 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.

  2. 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: http://dx.doi.org/10.1007/BF02762037

2004

  1. 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: http://dx.doi.org/10.13140/2.1.1963.4888

  2. 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: http://dx.doi.org/10.13140/2.1.4060.6407

  3. 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

2003

  1. 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.

1998

  1. P. Wijekoon; (1998). A comparison of the Restricted Ridge Regression and the Modified Ridge Regression estimators. Ceylon Journal of Science : Physical Sciences, 5(I): 75 – 79.

1995

  1. P. Wijekoon 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

1991

  1. 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: http://dx.doi.org/10.1080/03610929108830618

1989

  1. 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

  2. P. Wijekoon 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