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Papers 【 display / non-display 】

• Adaptation of the Mahalanobis–Taguchi Method to Ordinal Scale

  IWAMOTO Hiroki, NAGATA Yasushi

  Total Quality Science   8 ( 1 )   14 - 22   2022.12  [Reviewed]

  DOI CiNii Research

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  Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：一般社団法人 日本品質管理学会   Joint Work  

  <p>The Mahalanobis–Taguchi (MT) method is a multivariate analysis method that addresses problems such as pattern recognition and anomaly detection wherein outliers from data groups are detected. The MT method is applied to various other fields (e.g., medical examination, corporate bankruptcy discrimination, and employee turnover discrimination). At the time of application, the effectiveness of the MT method for scale data, other than continuous variables, has not been clarified. The MT method using the polyserial and polychoric correlation (MTP) method, which is an MT method using the Mahalanobis distance calculated by Pearson, polyserial and polychoric correlation coefficients, is proposed. Correlations between continuous variables are calculated using Pearson’s correlation coefficient, continuous and ordinal-scale variables are calculated using the polyserial correlation coefficient, and ordinal-scale variables are calculated using the polychoric correlation coefficient. Through simulation with artificial data, it was confirmed that the anomaly detection accuracy of the MT method decreased with respect to the ordinal scale and the correlation weakening by ordinal scaling can be eliminated using the polyserial and polychoric correlation coefficients. The results of this study indicate that the abnormality discrimination accuracy of the MTP method exceeds that of the MT method, although in a limited environment.</p>

• The Relationship between Work-Life Balance Assisting Measures and Women's Career Advancement

  IWAMOTO Hiroki, SUZUKI Hideo

  Journal of the Japan Society for Management Information   30 ( 4 )   245 - 258   2022.3  [Reviewed]

  DOI CiNii Research

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  Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Managemant Information   Joint Work  

  <p>The participation of women in the labor force has been increasing all over the world. Even in Japan, the participation of women in the workforce is progressing. However, it has been pointed out the ratio of female managers in Japan is low compared to Western countries but as well as Asian countries. Work-life balance (WLB) is an important factor that affects the women’s career advancement. This study focuses on the relationships between measures, and the impact on women’s career advancement. The results show that it is effective to reduce the monthly average overtime for the female employee ratio, to adopt the home-working program for female managers ratio, and to adopt the home-working program and day care facility or allowance program for female general manager or higher positions ratio. In addition, it suggests that setting up the environment by adopting in order from basic measures rather than each measure individually leads to enabling their measures.</p>

• Evaluation of personnel-adjusted added value: Estimating its relationship with future profit in Japan

  Iwamoto, H; Suzuki, H

  COGENT ECONOMICS & FINANCE   9 ( 1 )   2021.1  [Reviewed]

  DOI Web of Science

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  Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Joint Work  

• A Slacks-Based DEA-R Approach with an Application to Japanese Banks

  Wang Xu, Iwamoto Hiroki, Hasuike Takashi

  Journal of Advanced Computational Intelligence and Intelligent Informatics   30 ( 1 )   67 - 77   2026.1  [Reviewed]

  DOI Web of Science CiNii Research

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  Language：English   Publishing type：Research paper (scientific journal)   Publisher：富士技術出版株式会社   Joint Work  

  <p>Data envelopment analysis (DEA) is a powerful approach for evaluating the relative efficiency of decision-making units with multiple inputs and outputs. Integrating DEA with ratio analysis has become essential because of the increasing prevalence of ratio data (e.g., return on assets) in practical applications. This study develops a novel DEA-R model and the RAM-R model, which combines the well-established range-adjusted measure (RAM) with ratio analysis. The model effectively handles ratio data, accommodates negative values, and accounts large variations across indicators, thereby enhancing flexibility and robustness in efficiency evaluation. A case study of 93 Japanese banks compares the RAM-R model with the RAM and another slacks-based DEA-R (the slacks-based measure-R and SBM-R) models using ratio data to demonstrate its effectiveness in evaluating efficiency.</p>

• Improving the accuracy of robust parameter design by utilizing effective explanatory factors

  Mori Nayuta, Iwamoto Hiroki, Nagata Yasushi

  Total Quality Science   11 ( 1 )   1 - 11   2025.11  [Reviewed]

  DOI CiNii Research

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  Language：English   Publishing type：Research paper (scientific journal)   Publisher：一般社団法人 日本品質管理学会   Joint Work  

  Robust parameter design (RPD) is used in the Taguchi Method to reduce variability in system outputs and enhance quality. The technology development process utilizing RPD comprises an evaluation component for assessing robustness and a mechanism analysis component for devising new systems if the objectives are unmet. In this study, we focus on the Causality Search T-Method (CS-T method), an efficient method for mechanism analysis, and its development method, Knowledge Search-Instrumental variables (KS -IV). The CS-T method is a practical technique that can improve the efficiency of system selection while maintaining the efficiency of an RPD. However, the conditions under which these methods can be used with high accuracy and validity remain unclear. In this study, we propose an extension of the CS-T and KS-IV methods for dynamic parameter design. In addition, we discuss the differences between the data aggregation methods of the two methods and the relationship between the aggregation contents and results, and based on these discussions, we improve the accuracy and interpretability of the methods.

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