Updated on 2024/12/13

写真a

 
SAKAMOTO Wataru
 
Organization
Faculty of Environmental, Life, Natural Science and Technology Professor
Position
Professor
External link

Degree

  • Ph.D in Engineering ( 1998.3   Osaka University )

Research Interests

  • Statistical Science

Research Areas

  • Informatics / Statistical science  / 計算統計学,正則化法,ベイズ統計

Education

  • Osaka University   大学院基礎工学研究科   数理系専攻 博士後期課程

    1995.4 - 1998.3

      More details

    Country: Japan

    researchmap

  • Osaka University   大学院基礎工学研究科   数理系専攻 博士前期課程

    1993.4 - 1995.3

      More details

  • Kyoto University   理学部  

    1989.4 - 1993.3

      More details

    Notes: 主として数学を専攻

    researchmap

Research History

  • Okayama University   学術研究院環境生命自然科学学域(工学系)   Professor

    2023.4

      More details

    Country:Japan

    Notes:組織変更

    researchmap

  • Okayama University   学術研究院環境生命科学学域   Professor

    2021.4 - 2023.3

      More details

    Country:Japan

    Notes:組織変更(教教分離)

    researchmap

  • Okayama University   Division of Human Ecology, Graduate School of Environmental and Life Science   Professor

    2013.4 - 2021.3

      More details

    Country:Japan

    researchmap

  • Osaka University   Graduate School of Engineering Science Department of Systems Innovation Division of Mathematical Science   Associate Professor

    2007.4 - 2013.3

      More details

    Country:Japan

    Notes:職名変更

    researchmap

  • Osaka University   Graduate School of Engineering Science Department of Systems Innovation Division of Mathematical Science   Associate Professor (as old post name)

    2003.10 - 2007.3

      More details

▼display all

Professional Memberships

▼display all

Committee Memberships

  • 日本統計学会   代議員  

    2021.4 - 2023.3   

      More details

    Committee type:Academic society

    researchmap

  • 情報・システム研究機構・統計数理研究所   統計思考院運営委員会  

    2017.2 - 2019.3   

      More details

    Committee type:Other

    researchmap

  • The Asian Regional Section of the International Association for Statistical Computing   Board of Directors member  

    2016.1 - 2019.12   

      More details

    Committee type:Academic society

    researchmap

  • International Association for Statistical Computing   Scientific Secretary  

    2009.8 - 2011.8   

      More details

    Committee type:Academic society

    researchmap

  • 日本計算機統計学会   評議員・理事  

    2001.1   

      More details

    Committee type:Academic society

    評議員 (2003-2016, 2018-2020)
    庶務理事 (2001-2006)
    企画理事 (2007-2010)
    渉外理事 (2013-2014)
    欧文誌編集理事 (2015-2018)
    国際交流理事 (2019-2020)

    researchmap

▼display all

 

Papers

  • Spatio-temporal clustering analysis using generalized lasso with an application to reveal the spread of Covid-19 cases in Japan Reviewed

    Septian Rahardiantoro, Wataru Sakamoto

    Computational Statistics   39   1513 - 1537   2023.4

     More details

    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    DOI: 10.1007/s00180-023-01331-x

    researchmap

    Other Link: https://link.springer.com/article/10.1007/s00180-023-01331-x/fulltext.html

  • Bias‐reduced marginal Akaike information criteria based on a Monte Carlo method for linear mixed‐effects models Reviewed International journal

    Wataru Sakamoto

    Scandinavian Journal of Statistics   46 ( 1 )   87 - 115   2019.3

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Wiley  

    DOI: 10.1111/sjos.12339

    researchmap

    Other Link: https://onlinelibrary.wiley.com/doi/full-xml/10.1111/sjos.12339

  • Statistical Issues on Japanese Criteria of Metabolic Syndrome Reviewed

    SAKAMOTO Wataru, ISOGAWA Naoki, GOTO Masashi

    Kodo Keiryogaku   35 ( 2 )   177 - 192   2008

     More details

    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Behaviormetric Society of Japan  

    The article by The Examination Committee of Criteria for 'Obesity Disease' in Japan and Japan Society for the Study of Obesity (2002) established cut-off points of waist circumference at 85 cm for males and 90 cm for females as criteria of obesity disease. Their article has also become a basis for criteria of metabolic syndrome in Japan; however, their article has various problems on statistical aspects. How the criteria on waist circumference should vary was investigated through reexamination based on descriptions in their article. First, their article obtained criteria on visceral fat area (VFA) from data in which males and females were pooled, while our reexamination suggested that we should use separate criteria on VFA between males and females. Second, their article inappropriately used regression lines to estimate waist circumference corresponding to VFA cut-off points. Our reexamination with errors-in-variables models suggested alternative cut-off points of waist circumference at 87 cm for males and 85 cm for females. Our simulation confirmed that the criteria by their article might lead to inappropriate diagnosis which is strict for males and easy for females.

    DOI: 10.2333/jbhmk.35.177

    CiNii Article

    researchmap

  • 罰則付きスプラインによる非線形回帰構造の推測 Reviewed

    坂本 亘, 井筒理人, 白旗慎吾

    計算機統計学   21 ( 1-2 )   55 - 94   2008

     More details

    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)  

    researchmap

  • EXTRACTING NON-LINEAR ADDITIVE REGRESSION STRUCTURE WITH POWER-ADDITIVE SMOOTHING SPLINES Reviewed

    Sakamoto Wataru

    Journal of the Japanese Society of Computational Statistics   20 ( 1 )   83 - 108   2007

     More details

    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Japanese Society of Computational Statistics  

    The additive regression model assumes additivity among explanatory variables and other rigid requirements, which might give poor estimation of regression functions. Transforming response variables is a useful method to diagnose additivity and other requirements. From a practical point of view, parametric transformations such as the Box-Cox power transformation would give more helpful suggestions in interpreting results of analysis than nonparametric transformations. The power additive smoothing spline (PASS) model is proposed to diagnose the validity of assuming additivity in the additive regression model. The smooth functions (and often regression parameters) are estimated with a penalized likelihood approach, and the power and the smoothing parameters, which govern global nonlinear regression structure, are estimated with the empirical Bayes method, in which a Laplace approximation of the marginal likelihood is developed. The PASS model is applied to some data sets, and also its performance is examined through a simulation experiment. It is shown that the PASS model can extract an appropriate regression structure if true structure is additive after a Box-Cox power transformation of responses.

    DOI: 10.5183/jjscs1988.20.83

    CiNii Article

    CiNii Books

    researchmap

▼display all

Books

  • 統計学辞典

    白旗慎吾, 内田雅之, 熊谷悦生, 黒木 学, 阪本雄二, 坂本 亘

    共立出版  2010.10  ( ISBN:9784320019393

     More details

    Total pages:vi, 512p   Language:Japanese

    CiNii Books

    researchmap

MISC

  • Inference on variance components near boundary in linear mixed effect models Reviewed

    Wataru Sakamoto

    Wiley Interdisciplinary Reviews: Computational Statistics   11 ( 6 )   2019.11

     More details

    Language:English   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)   Publisher:Wiley  

    DOI: 10.1002/wics.1466

    researchmap

    Other Link: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/wics.1466

  • p 値と仮説検定:どう教えればよいか

    坂本 亘

    2017年度統計関連学会連合大会 講演報告集   2017.9

     More details

    Language:Japanese   Publishing type:Research paper, summary (national, other academic conference)  

    researchmap

  • Cluster detection of disease mapping data based on latent Gaussian Markov random field models Reviewed

    Sakamoto, W

    Proceedings of COMPSTAT 2016: 22th International Conference on Computational Statistics (Oviedo, Spain)   267 - 277   2016.8

     More details

    Language:English   Publishing type:Article, review, commentary, editorial, etc. (international conference proceedings)  

    researchmap

  • 医学統計概論―多変量解析とは―

    坂本 亘, 後藤昌司

    日本心血管インターベンション治療学会誌   2 ( 4 )   295 - 302   2010

     More details

    Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

    researchmap

  • MARS: selecting basis and knots with the empirical Bayes method Reviewed

    Sakamoto, W

    Compstat 2006: Proceedings in Computational Statistics (CD-ROM) (Rome, Italy)   1397 - 1404   2006.8

     More details

    Language:English   Publishing type:Article, review, commentary, editorial, etc. (international conference proceedings)  

    researchmap

▼display all

Presentations

  • Analysis of disease mapping data: how to detect clusters of higher prevalence more flexibly Invited

    Sakamoto, W

    ICMSDS 2020 (Bogor, Indonesia: Online)  2020.11.11 

     More details

    Language:English   Presentation type:Oral presentation (invited, special)  

    researchmap

  • Analysis of Spatial Data with a Gaussian Mixture Markov Random Field Model

    Sakamoto, W

    IASC-ARS/NZSA 2017  2017.12 

     More details

    Language:English   Presentation type:Oral presentation (general)  

    researchmap

  • Cluster detection of disease mapping data based on latent Gaussian Markov random field models Invited

    Wataru Sakamoto

    2016 IASC-ARS Conference (Daejeon, Korea)  2016.11 

     More details

    Language:English   Presentation type:Oral presentation (invited, special)  

    researchmap

  • Spatially varying coefficient modeling of numerical and categorical predictor variables in the generalized lasso

    Septian Rahardiantoro, Wataru Sakamoto

    IASC-ARS2022  2022.2.23 

     More details

    Event date: 2022.2.21 - 2022.2.24

    Language:English   Presentation type:Oral presentation (general)  

    researchmap

  • 馬蹄事前分布を用いたスパース回帰モデルの選択

    坂本 亘

    第6回かごしまデータ科学シンポジウム  2024.8.5 

     More details

    Language:Japanese   Presentation type:Oral presentation (general)  

    researchmap

▼display all

Awards

  • IASC Young Researchers Award

    2006.9   COMPSTAT2006 (Rome, Italy)  

     More details

Research Projects

  • Effective inference and selection of statistical models to represent latent structure in spatial data

    Grant number:26330042  2014.04 - 2017.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)  Grant-in-Aid for Scientific Research (C)

    Sakamoto Wataru

      More details

    Grant amount:\4160000 ( Direct expense: \3200000 、 Indirect expense:\960000 )

    Some methods of making effective inference and selection in statistical models with high-dimensional latent variables are considered to reveal complicated latent structure in spacial and geographical data. It was shown that the method of detecting regions using estimated spatial effect, proposed for application to disease mapping data, had higher possibility of detecting regions with high risk than existing methods. Also it was suggested that the model selection method considered in the analysis of cancer mortality data with age-period-cohort (APC) models could estimate each effect appropriately, and give a new knowledge for interpretation.

    researchmap

  • Selecting an optimal mixed effect model based on simulation : theory and applications

    Grant number:21500275  2009 - 2011

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)  Grant-in-Aid for Scientific Research (C)

    SAKAMOTO Wataru

      More details

    Grant amount:\3250000 ( Direct expense: \2500000 、 Indirect expense:\750000 )

    Mixed effect models are useful for analysis of data which are measured repeatedly for each individual, and have been applied to various fields such as medical and biological sciences. However, how to select an optimal mixed effect model has not been fully examined. We proposed a criterion to select such an optimal model, which would be appropriate in theory and practically more useful. The criterion can be computed approximately by using random numbers. We confirmed that the proposed criterion should lessen risk of choosing a parsimonious model wrongly.

    researchmap

  • ノンパラメトリック回帰による多次元構造の探索:推定方式の改良と実装

    Grant number:17700280  2005 - 2007

    日本学術振興会  科学研究費助成事業  若手研究(B)

    坂本 亘

      More details

    Grant amount:\3100000 ( Direct expense: \3100000 )

    本研究は、非線形構造の探索・診断という観点からノンパラメトリック回帰の方法論を再整備し、ノンパラメトリック回帰をより強力な探索的データ解析の道具にすることを目的とした。とくに交互作用効果を含む多次元ノンパラメトリック回帰モデルの有用性を探った。
    前年度までに提案・開発した、多変量適応的回帰スプライン(MARS)における経験Bayes法による基底関数および節点の選定方式は、Friedman による従来の方式(一般化交差確認法の利用)での回帰構造の解釈などの難点を克服することを目標としている。これについて、本年度は以下のような研究を行った。
    1.変数寄与の測度の再検討
    回帰構造の解釈に必要となる、各々の説明変数の寄与(主効果・交互作用効果)の測度について、従来の「相対重要度」はかなりアドホックな定義であった。より合理的・包括的な測度として、分散分析などで用いられる平方和分解に類似した変動の分解に基づいて、条件付き分散を用いて定義することを検討した。
    2.シミュレーションなどによる性能評価
    前述の条件付き分散に基づく測度を用いて、従来の方式(Friedmanが提案した交差確認法などによる方法)に比べて、回帰構造、とくに交互作用効果を正しく抽出できることを実証した。

    researchmap

  • ノンパラメトリック回帰による非線形構造の探索とその実装

    Grant number:14780171  2002 - 2004

    日本学術振興会  科学研究費助成事業  若手研究(B)

    坂本 亘

      More details

    Grant amount:\3100000 ( Direct expense: \3100000 )

    本研究の目標は,データの背後にある複雑な非線形構造を探索・抽出するための道具として,ノンパラメトリック回帰,とくに平滑化スプラインの有用性を実証し,その方法を実装したアプリケーションを開発することであった。
    本年度に実施した研究内容は以下のとおりである。
    1.応答のベキ変換による加法モデルの拡張
    加法モデルにおける仮定(加法性,分散均一性,正規性など)の妥当性を評価するために,ベキ加法化平滑化スプラインやベキ重み付き平滑化スプラインなどを提案し,Fortranプログラムによる実装を行った。応答のベキ変換パラメータを分散・平滑化パラメータと同時に最大周辺尤度法(経験Bayes法)によって選定する。ベキ加法化平滑化スプラインでは周辺尤度の正確な計算は困難であるため,その近似方式を提案した。本方式の近似精度,および本方式を用いた場合の加法関数の推定性能を,事例研究やシミュレーションを通じて評価し,推定されるベキ変換が非線形構造を考慮しながら加法性や分散均一性などの要件を達成するという妥当な結果を得ることができた。
    2.ABIC(赤池Bayes情報量基準)による最適なモデルの選定
    平滑化スプラインの線形混合モデルによる表現を利用することにより,包括的な階層型のモデル族を構築することが可能となる。モデルが非線形(ノンパラメトリック)成分を含むかどうかの診断は,線形混合モデルのランダム効果に関する診断に帰着され,必要となる分散パラメータの個数の選定にはABICを用いることができる。本方式の有用性を事例研究などにより確認した。

    researchmap

  • Refinement and improvement of microsimulation for colorectal cancer risk assessment

    Grant number:22K10559  2022.04 - 2026.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    加茂 憲一, 福井 敬祐, 坂本 亘

      More details

    Grant amount:\4030000 ( Direct expense: \3100000 、 Indirect expense:\930000 )

    researchmap

▼display all

 

Class subject in charge

  • Simulation Statistics (2024academic year) Late  - 火7~8

  • Technical English (2024academic year) 3rd and 4th semester  - [第3学期]水3~4, [第4学期]水1~2

  • Basic of Information Technology, Electrical Engineering, and Mathematical and Data Sciences (2024academic year) 1st semester  - 水1~2

  • Basic Mathematical and Data Sciences (2024academic year) Third semester  - 木5~6

  • Mathematical and Data Sciences(Advanced) (2024academic year) Fourth semester  - 火1~2

▼display all

 

Academic Activities

  • Associate Editor, Japanese Journal of Statistics and Data Science International contribution

    Role(s):Peer review

    2023.1.1

     More details

    Type:Peer review 

    researchmap

  • Computational Statistics: Editor-in-Chief

    Role(s):Planning, management, etc., Peer review

    2018.7.1 - 2020.12.31

     More details

    Type:Peer review 

    researchmap

  • 2015年度統計関連学会連合大会(運営委員長)

    Role(s):Planning, management, etc.

    2015.9.6 - 2015.9.9

     More details

    Type:Competition, symposium, etc. 

    researchmap

  • Editor, Journal of the Japanese Society of Computational Statistics

    Role(s):Planning, management, etc., Peer review

    2015.1.1 - 2018.4.30

     More details

    Type:Academic society, research group, etc. 

    researchmap

  • Data Science, Statistics and Visualization

    Role(s):Planning, management, etc.

    2019.8.13 - 2019.8.15

     More details

    Type:Competition, symposium, etc. 

    researchmap

▼display all