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題名 Cosine similarity as a sample size-free measure to quantify phase clustering within a single neurophysiological signal
作者 周珮婷
徐慎謀
Chou, Elizabeth P.
Hsu, Shen-Mou
貢獻者 統計系
關鍵詞 Cosine similarity; ITC; Oscillations; Phase; Phase clustering
日期 2018-02
上傳時間 24-Jan-2018 17:31:29 (UTC+8)
摘要 Background : Phase clustering within a single neurophysiological signal plays a significant role in a wide array of cognitive functions. Inter-trial phase coherence (ITC) is commonly used to assess to what extent phases are clustered in a similar direction over samples. However, this measure is especially dependent on sample size. Although ITC was transformed into ITCz, namely, Rayleigh’s Z, to “correct” for the sample-size effect in previous research, the validity of this strategy has not been formally tested. New method This study introduced cosine similarity (CS) as an alternative solution, as this measure is an unbiased and consistent estimator for finite sample size and is considered less sensitive to the sample-size effect. Results : In a series of studies using either artificial or real datasets, CS was robust against sample size variation even with small sample sizes. Moreover, several different aspects of examinations confirmed that CS could successfully detect phase-clustering differences between datasets with different sample sizes. Comparison with existing methods Existing measures suffer from sample-size effects. ITCz produced a mixed pattern of bias in assessing phase clustering according to sample size, whereas ITC overestimated the degree of phase clustering with small sample sizes. Conclusions : The current study not only reveals the incompetence of the previous “correction” measure, ITCz, but also provides converging evidence showing that CS may serve as an optimal measure to quantify phase clustering.
關聯 Journal of Neuroscience Methods, Volume 295, Pages 111-120
資料類型 article
DOI https://doi.org/10.1016/j.jneumeth.2017.12.007
dc.contributor 統計系-
dc.creator (作者) 周珮婷zh_TW
dc.creator (作者) 徐慎謀zh_TW
dc.creator (作者) Chou, Elizabeth P.en_US
dc.creator (作者) Hsu, Shen-Mouen_US
dc.date (日期) 2018-02-
dc.date.accessioned 24-Jan-2018 17:31:29 (UTC+8)-
dc.date.available 24-Jan-2018 17:31:29 (UTC+8)-
dc.date.issued (上傳時間) 24-Jan-2018 17:31:29 (UTC+8)-
dc.identifier.uri (URI) http://nccur.lib.nccu.edu.tw/handle/140.119/115627-
dc.description.abstract (摘要) Background : Phase clustering within a single neurophysiological signal plays a significant role in a wide array of cognitive functions. Inter-trial phase coherence (ITC) is commonly used to assess to what extent phases are clustered in a similar direction over samples. However, this measure is especially dependent on sample size. Although ITC was transformed into ITCz, namely, Rayleigh’s Z, to “correct” for the sample-size effect in previous research, the validity of this strategy has not been formally tested. New method This study introduced cosine similarity (CS) as an alternative solution, as this measure is an unbiased and consistent estimator for finite sample size and is considered less sensitive to the sample-size effect. Results : In a series of studies using either artificial or real datasets, CS was robust against sample size variation even with small sample sizes. Moreover, several different aspects of examinations confirmed that CS could successfully detect phase-clustering differences between datasets with different sample sizes. Comparison with existing methods Existing measures suffer from sample-size effects. ITCz produced a mixed pattern of bias in assessing phase clustering according to sample size, whereas ITC overestimated the degree of phase clustering with small sample sizes. Conclusions : The current study not only reveals the incompetence of the previous “correction” measure, ITCz, but also provides converging evidence showing that CS may serve as an optimal measure to quantify phase clustering.en_US
dc.format.extent 1986287 bytes-
dc.format.mimetype application/pdf-
dc.relation (關聯) Journal of Neuroscience Methods, Volume 295, Pages 111-120-
dc.subject (關鍵詞) Cosine similarity; ITC; Oscillations; Phase; Phase clusteringen_US
dc.title (題名) Cosine similarity as a sample size-free measure to quantify phase clustering within a single neurophysiological signalen_US
dc.type (資料類型) article-
dc.identifier.doi (DOI) 10.1016/j.jneumeth.2017.12.007-
dc.doi.uri (DOI) https://doi.org/10.1016/j.jneumeth.2017.12.007-