Niels Keiding was born on 14 May 1944 in Copenhagen, Denmark and died on 3 March 2022. He grew up in a suburb North of Copenhagen as the oldest of three children; with two younger sisters. Their father was a biologist working with insects that are pests for agriculture. By following his father's work, Niels realised early that he would also work with biological data, and in high school, decided he wanted to become a biostatistician. Niels was excellent at mathematics, and other important interests included scouting. His keen interest in nature continued throughout his life.

Niels became ‘cand.stat.’ (master of statistics) in 1968—at that time, a relatively newly established programme at the University of Copenhagen. After graduation, he did his military service working with analyses of intelligence tests for the conscripts. His early professional career was as an assistant/associate professor in the Department of Mathematical Statistics at the University of Copenhagen. This was a very strong department with a young and active staff. Head of Department was Professor Anders Hald, who was also Niels's Masters thesis advisor. Though strong in mathematics, Niels work also emphasised applications in cooperation with researchers from other subject areas, mostly in medicine. Niels never took a PhD, in fact, he was proud of never having needed his certificate for completion of his Masters degree. In 2005, he was awarded an Honorary Doctorate by the University of Bordeaux, France. Niels was a founding member of the Danish Society of Theoretical Statistics in 1971 (serving as secretary from 1971 to 1975) and was among those who took the initiative to establish the Scandinavian Journal of Statistics in 1974.

In 1978, Niels helped to establish the ‘Statistical Research Unit’ which was financed for 5 years by Danish Research Councils. Later this developed into the Section of Biostatistics at the Faculty of Health Sciences at the University of Copenhagen, which is now a well-established centre for biostatistics in Denmark. Niels became a full professor there in 1984 and he was the head of the Section until 3 years before he retired in 2014. He then became professor emeritus at the section and kept working actively throughout his retirement.

Through the establishment of the Statistical Research Unit, Niels had an enormous impact on Danish biostatistics. Through his work in various (bio)statistical societies, he also influenced statistics internationally. He was treasurer of the Bernoulli Society of Mathematical Statistics and Probability (1981–1987); chairman of the board of the Scandinavian Journal of Statistics (1988–1991); editor of part of the journal Biometrics (1988–1992); vice president (1991 and 1994) and President (1992–1993) of The International Biometric Society. He served on the Research Section Committee of the Royal Statistical Society (1999–2003) and was a member of Council and several ad hoc committees with the Institute of Mathematical Statistics (USA) and International Statistical Institute (ISI). He was vice president (1997–99), President-elect (2003–2005) and President (2005–2007) of the ISI. In addition, he was an editor of both the Monographs Series and the Interdisciplinary Statistics Series of Chapman & Hall/CRC, serving on both boards for 25 years.

In recognition of his achievements, Niels received a number of honours, including: election to International Statistical Institute (1978); fellow of the Institute of Mathematical Statistics (USA) (1987); and the Marvin Zelen Leadership Award in Statistical Science (Harvard School of Public Health, 2001). He was elected as Foreign Member of The Norwegian Academy of Science and Letters, (2005); an honorary Life Member of the International Biometric Society (2008); and Norman E. Breslow lecturer in the Department of Biostatistics, University of Washington, Seattle (2010); Niels was also a member of Academia Europaea, (2011) and was elected an honorary Life Member of the Danish Society of Theoretical Statistics (2015).

Niels authored or co-authored several important publications, including early work on branching processes as well as a number of publications dealing with the history of statistics. He helped to establish the group of authors of Statistical Models Based on Counting Processes, the highly-cited Springer book by Andersen, Borgan, Gill and Keiding (1993). He published work showing his interest in demography and time-to-pregnancy and, more recently, he co-authored review papers on statistical methodology in epidemiology.

He supervised several PhD students in biostatistics or epidemiology and he was active in university administration as well as in national and international evaluations of research proposals, academic positions, and scientific theses.

On a personal note, Niels was married twice—both his wives were medical doctors. With his first wife, Susanne, he had a son and a daughter and he had five grandchildren. Rather later in life, Niels divorced his first wife and married Else with whom he enjoyed his retirement travelling, attending cultural events and bird-watching.

As a working biostatistician and being active as an orienteer, Niels always emphasised that ‘in case of discrepancy between map and terrain—always follow the terrain!’ This is, obviously, important in orienteering and in biostatistics as it means that where a model does not fit the data, then modify the model, that is do not force a non-fitting model onto your data.

Niels was a very good colleague and showed great leadership. He was insightful, always willing to help and had a well-developed sense of humour. He was a great inspiration for all of our profession.

Niels Keiding 于 1944 年 5 月 14 日出生于丹麦哥本哈根，并于 2022 年 3 月 3 日去世。他在哥本哈根北部郊区长大，是三个孩子中的老大。和两个妹妹。他们的父亲是一名生物学家，研究对农业有害的昆虫。通过跟随父亲的工作，尼尔斯很早就意识到他也会处理生物数据，并在高中时决定成为一名生物统计学家。尼尔斯擅长数学，其他重要兴趣包括童子军。他对自然的浓厚兴趣贯穿了他的一生。

尼尔斯成为“cand.stat”。（统计学硕士）在 1968 年——当时，哥本哈根大学的一个相对较新的项目。毕业后，他在服兵役期间为应征入伍者分析智力测试。他早期的职业生涯是在哥本哈根大学数理统计系担任助理/副教授。这是一个非常强大的部门，拥有年轻而活跃的员工。系主任是 Anders Hald 教授，他也是 Niels 的硕士论文导师。虽然在数学方面很强大，但 Niels 的工作也强调与其他学科领域的研究人员合作的应用，主要是在医学领域。Niels 从未获得过博士学位，事实上，他为自己的硕士学位不需要证书而感到自豪。2005 年，他被法国波尔多大学授予荣誉博士学位。Niels 是 1971 年丹麦理论统计学会的创始成员（1971 年至 1975 年担任秘书），是主动建立斯堪的纳维亚统计杂志， 1974 年。

1978 年，尼尔斯帮助建立了“统计研究单位”，由丹麦研究委员会资助了 5 年。后来，这发展成为哥本哈根大学健康科学学院的生物统计学系，该学院现在是丹麦一个成熟的生物统计学中心。Niels 于 1984 年成为该部门的正教授，并担任该部门的负责人，直到 3 年才于 2014 年退休。随后，他成为该部门的名誉教授，并在退休期间一直积极工作。

通过建立统计研究部，尼尔斯对丹麦的生物统计学产生了巨大的影响。通过他在各种（生物）统计学会的工作，他还影响了国际统计学。他是伯努利数理统计和概率学会的财务主管（1981-1987）；斯堪的纳维亚统计杂志董事会主席（1988-1991）；Biometrics杂志部分编辑（1988-1992）；国际生物识别学会副主席（1991 年和 1994 年）和主席（1992-1993 年）。他曾在皇家统计学会研究部委员会任职（1999-2003 年），并且是数理统计研究所（美国）和国际统计研究所（ISI）理事会和多个特设委员会的成员。He was vice president (1997–99), President-elect (2003–2005) and President (2005–2007) of the ISI. 此外，他还是 Chapman & Hall/CRC 的专着系列和跨学科统计系列的编辑，在两个委员会任职 25 年。

为了表彰他的成就，尼尔斯获得了许多荣誉，包括：选举国际统计研究所（1978年）；数理统计研究所研究员（美国）（1987 年）；和 Marvin Zelen 统计科学领导奖（哈佛大学公共卫生学院，2001 年）。He was elected as Foreign Member of The Norwegian Academy of Science and Letters, (2005); 国际生物识别学会荣誉终身会员（2008 年）；和 Norman E. Breslow，西雅图华盛顿大学生物统计学系讲师（2010 年）；Niels 还是 Academia Europaea 的成员（2011 年），并被选为丹麦理论统计学会的荣誉终身会员（2015 年）。

Niels 撰写或合着了几本重要的出版物，包括关于分支过程的早期工作以及一些涉及统计历史的出版物。他帮助建立了基于计数过程的统计模型的作者小组，这是 Andersen、Borgan、Gill 和 Keiding（1993 年）高度引用的 Springer 著作。他发表的作品表明了他对人口统计学和怀孕时间的兴趣，最近，他与人合着了关于流行病学统计方法的评论论文。

他指导了几名生物统计学或流行病学博士生，并积极参与大学管理以及对研究提案、学术职位和科学论文的国内和国际评估。

就个人而言，尼尔斯结过两次婚——他的妻子都是医生。他与第一任妻子苏珊娜育有一子一女，并育有五个孙子孙女。尼尔斯在晚年与他的第一任妻子离婚并嫁给了埃尔斯，与埃尔斯一起享受退休旅行、参加文化活动和观鸟。

作为一名工作的生物统计学家和作为一名定向运动爱好者，尼尔斯总是强调“如果地图和地形之间存在差异，请始终遵循地形！” 显然，这在定向运动和生物统计学中很重要，因为这意味着模型不适合数据的地方，然后修改模型，即不要将不适合的模型强加到您的数据上。

Niels 是一位非常好的同事，并表现出出色的领导能力。他很有洞察力，总是乐于助人，并且有很好的幽默感。他对我们所有的职业都有很大的启发。