Sains Malaysiana 41(6)(2012): 769-778

 

On Discordance Test for the Wrapped Normal Data

(Ujian Tak Sejajar bagi Data Normal Balutan)



Adzhar Rambli1, Mohd Ikhwan Abdulah1, Safwati Ibrahim1, Abdul Ghapor Hussin2 & Ibrahim Mohamed1*

1Institute of Mathematical Sciences University of Malaya, Kuala Lumpur, Malaysia

 

2Centre for Foundation studies in Sciences, University of Malaya, Kuala Lumpur, Malaysia

 

Received: 7 July 2011 / Accepted: 30 December 2011

 

ABSTRACT

This paper focuses on detecting outliers in the circular data which follow the wrapped normal distribution. We considered four discordance tests based on M, C, D and A statistics. The cut-off points of the four tests were obtained and the performance of the detection procedures was studied via simulations. In general, we showed that the discordance test based on the A statistic outperforms the other tests in all cases. For illustration, the city of Kuantan wind direction data set was considered.

 

Keywords: A statistics; circular; discordance; outlier; wrapped normal distribution

 

 

ABSTRAK

Kajian ini tertumpu kepada pengesanan nilai tersisih yang wujud di dalam data bulatan terutamanya data bertaburan normal balutan. Empat ujian sejajar berdasarkan statistik sepertiM, C, D dan A dipertimbangkan. Titik potongan dan prestasi prosedurbagi mengesan nilai tersisih diperoleh melalui kajian simulasi. Secara amnya, dibuktikan bahawa ujian tak sejajar berdasarkan statistikA adalah lebih baik berbanding statistik yang lain untuk kesemua kes. Sebagai contoh, data arah angin bandar Kuantan telah digunakan sebagai contoh.

 

Kata kunci: Bulatan; nilai tersisih; statistikA; taburan normal balutan

 

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*Corresponding author, email: imohamed@um.edu.my

 

 

 

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