著者

Etsuji Suzuki Tomohiro Shinozaki Eiji Yamamoto

出版者

Japan Epidemiological Association

雑誌

Journal of Epidemiology (ISSN:09175040)

巻号頁・発行日

pp.JE20190192, (Released:2020-02-01)

参考文献数

70

被引用文献数

9 34

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Graphical models are useful tools in causal inference, and causal directed acyclic graphs (DAGs) are used extensively to determine the variables for which it is sufficient to control for confounding to estimate causal effects. We discuss the following ten pitfalls and tips that are easily overlooked when using DAGs: 1) Each node on DAGs corresponds to a random variable and not its realized values; 2) The presence or absence of arrows in DAGs corresponds to the presence or absence of individual causal effect in the population; 3) “Non-manipulable” variables and their arrows should be drawn with care; 4) It is preferable to draw DAGs for the total population, rather than for the exposed or unexposed groups; 5) DAGs are primarily useful to examine the presence of confounding in distribution in the notion of confounding in expectation; 6) Although DAGs provide qualitative differences of causal structures, they cannot describe details of how to adjust for confounding; 7) DAGs can be used to illustrate the consequences of matching and the appropriate handling of matched variables in cohort and case-control studies; 8) When explicitly accounting for temporal order in DAGs, it is necessary to use separate nodes for each timing; 9) In certain cases, DAGs with signed edges can be used in drawing conclusions about the direction of bias; and 10) DAGs can be (and should be) used to describe not only confounding bias but also other forms of bias. We also discuss recent developments of graphical models and their future directions.

著者

Etsuji Suzuki Michio Yamamoto Eiji Yamamoto

出版者

Japan Epidemiological Association

雑誌

Journal of Epidemiology (ISSN:09175040)

巻号頁・発行日

pp.JE20210352, (Released:2022-01-22)

参考文献数

26

被引用文献数

1

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Background: The counterfactual definition of confounding is often explained in the context of exchangeability between the exposed and unexposed groups. One recent approach is to examine whether the measures of association (e.g., associational risk difference) are exchangeable when exposure status is flipped in the population of interest. We discuss the meaning and utility of this approach, showing their relationships with the concept of confounding in the counterfactual framework.Methods: Three hypothetical cohort studies are used, in which the target population is the total population. After providing an overview of the notions of confounding in distribution and in measure, we discuss the approach from the perspective of exchangeability of measures of association (e.g., factual associational risk difference vs. counterfactual associational risk difference).Results: In general, if the measures of association are non-exchangeable when exposure status is flipped, confounding in distribution is always present, although confounding in measure may or may not be present. Even if the measures of association are exchangeable when exposure status is flipped, there could be confounding both in distribution and in measure. When we use risk difference or risk ratio as a measure of interest and the exposure prevalence in the population is 0.5, testing the exchangeability of measures of association is equivalent to testing the absence of confounding in the corresponding measures.Conclusions: The approach based on exchangeability of measures of association essentially does not provide a definition of confounding in the counterfactual framework. Subtly differing notions of confounding should be distinguished carefully.

著者

Kazufumi Nagata Yasunori Nonoue Kazuki Matsubara Ritsuko Mizobuchi Nozomi Ono Taeko Shibaya Kaworu Ebana Eri Ogiso-Tanaka Takanari Tanabata Kazuhiko Sugimoto Fumio Taguchi-Shiobara Jun-ichi Yonemaru Yusaku Uga Atsunori Fukuda Tadamasa Ueda Shin-ichi Yamamoto Utako Yamanouchi Toshiyuki Takai Takashi Ikka Katsuhiko Kondo Tomoki Hoshino Eiji Yamamoto Shunsuke Adachi Jian Sun Noriyuki Kuya Yuka Kitomi Ken Iijima Hideki Nagasaki Ayahiko Shomura Tatsumi Mizubayashi Noriyuki Kitazawa Kiyosumi Hori Tsuyu Ando Toshio Yamamoto Shuichi Fukuoka Masahiro Yano

出版者

Japanese Society of Breeding

雑誌

Breeding Science (ISSN:13447610)

巻号頁・発行日

vol.73, no.3, pp.332-342, 2023 (Released:2023-07-27)

参考文献数

64

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Many agronomic traits that are important in rice breeding are controlled by multiple genes. The extensive time and effort devoted so far to identifying and selecting such genes are still not enough to target multiple agronomic traits in practical breeding in Japan because of a lack of suitable plant materials in which to efficiently detect and validate beneficial alleles from diverse genetic resources. To facilitate the comprehensive analysis of genetic variation in agronomic traits among Asian cultivated rice, we developed 12 sets of chromosome segment substitution lines (CSSLs) with the japonica background, 11 of them in the same genetic background, using donors representing the genetic diversity of Asian cultivated rice. Using these materials, we overviewed the chromosomal locations of 1079 putative QTLs for seven agronomic traits and their allelic distribution in Asian cultivated rice through multiple linear regression analysis. The CSSLs will allow the effects of putative QTLs in the highly homogeneous japonica background to be validated.

著者

Etsuji Suzuki Michio Yamamoto Eiji Yamamoto

出版者

Japan Epidemiological Association

雑誌

Journal of Epidemiology (ISSN:09175040)

巻号頁・発行日

vol.33, no.8, pp.385-389, 2023-08-05 (Released:2023-08-05)

参考文献数

26

被引用文献数

1

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Background: The counterfactual definition of confounding is often explained in the context of exchangeability between the exposed and unexposed groups. One recent approach is to examine whether the measures of association (eg, associational risk difference) are exchangeable when exposure status is flipped in the population of interest. We discuss the meaning and utility of this approach, showing their relationships with the concept of confounding in the counterfactual framework.Methods: Three hypothetical cohort studies are used, in which the target population is the total population. After providing an overview of the notions of confounding in distribution and in measure, we discuss the approach from the perspective of exchangeability of measures of association (eg, factual associational risk difference vs counterfactual associational risk difference).Results: In general, if the measures of association are non-exchangeable when exposure status is flipped, confounding in distribution is always present, although confounding in measure may or may not be present. Even if the measures of association are exchangeable when exposure status is flipped, there could be confounding both in distribution and in measure. When we use risk difference or risk ratio as a measure of interest and the exposure prevalence in the population is 0.5, testing the exchangeability of measures of association is equivalent to testing the absence of confounding in the corresponding measures.Conclusion: The approach based on exchangeability of measures of association essentially does not provide a definition of confounding in the counterfactual framework. Subtly differing notions of confounding should be distinguished carefully.

著者

Emdadul Haque Eiji Yamamoto Kenta Shirasawa Hiroaki Tabuchi Ung-Han Yoon Sachiko Isobe Masaru Tanaka

出版者

Japanese Society for Root Research

雑誌

Plant Root (ISSN:18816754)

巻号頁・発行日

vol.14, pp.11-21, 2020 (Released:2020-10-09)

参考文献数

31

被引用文献数

6

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Genetic studies on the purple-fleshed sweetpotato (Ipomoea batatas L.), which is rich in anthocyanin (AN) in the storage root, were performed by polyploid GWAS based on the allele dosage probability using 59,675 SNPs obtained from 94 F1 progenies between the cultivars 'Konaishin' (which has a high yield but no AN) and 'Akemurasaki' (which has a high AN content but low to moderate yield). The distribution of relative AN content was highly biased, with 60% of clones showing a low to undetectable level (A530 < 0.5). Fifty-nine SNPs from six signals on homologous groups (HGs) 3, 5 (one major and one smaller signal), 7, 13, and 15 were strongly associated with the relative AN content. Twelve SNPs from the major signal and one from the smaller signal of HG 5 were further detected by QTL analysis. In a database search of the AN biosynthesis gene, transcription factors IbMYB1 and IbWD40 and AN structural genes IbF3H and IbDFR were located on HG 5, suggesting that an SNP marker or markers from HG 5 might be tightly linked to candidate gene(s) homologous to one of these transcription factors and AN structural genes as a major factor in determining AN accumulation in the storage roots. These results would enhance our understanding of the underlying genetic basis of AN accumulation in the storage roots of sweetpotatoes, and the SNP markers found here, especially 13 SNPs from HG 5, would be a potential platform for future marker-assisted selection for breeding high-AN sweetpotato varieties.

著者

山本 英司 Eiji Yamamoto 奈良産業大学経済学部

雑誌

奈良産業大学産業と経済 = Nara Sangyo University, the journal of industrial economics (ISSN:09159789)

巻号頁・発行日

vol.20, no.3, pp.123-146, 2005-09-30