Stef van Buuren, PhD, is a professor of Statistical Analysis of Incomplete Data at the University of Utrecht and statistician at the Netherlands Organisation for Applied Scientific Research TNO in Leiden. His interests include the analysis of incomplete data and child growth and development (h-index 61). Van Buuren is the inventor of the MICE algorithm for multiple imputation of missing data (>85.000 downloads per month) and has written the accessible monograph Flexible Imputation of Missing Data. Second Edition, CRC/Chapman & Hall. He designed the growth charts for the Dutch child health care system and invented the D-score, a new method for expressing child development on a quantitative scale. He consults for the World Health Organization and the Bill & Melinda Gates Foundation. More background at https://stefvanbuuren.name and software at https://github.com/stefvanbuuren. Iris Eekhout holds a double masters in clinical psychology and methodology and statistics of psychology (Leiden University). She obtained her PhD at the Department of Epidemiology and Biostatistics of the VU University medical centre in Amsterdam. Her dissertation work resulted in novel ways of dealing with missing data in questionnaire items and total scores. Currently, Iris teaches a course on missing data analysis in the epidemiology master’s program at VU University medical centre. At TNO, Iris works on a variety of projects as a methodologist and statistical analyst related to child health, e.g., measuring child development (D-score) and adaptive screenings for psycho-social problems (psycat). More background at https://www.iriseekhout.com and software at https://github.com/iriseekhout.