The authors would like to acknowledge the financial support of the Clinical Engineering Division of the International Federation for Medical & Biological Engineering to assist the preparation of the text, and particularly the visionary leadership and encouragement of Professor Saide Calil, who has done much to champion the introduction of human factors methods into the field of Clinical Engineering. In addition, thanks are due to the following people, who reviewed one or more sections of the text：Sandra Ahedo, Fernando Andrade, Guilherme Araujo Wood, Victor Batista Tsukahara, Ann Blandford, Saide Calil, Peter Doyle, Karina Gomide, Julie Greenall, Laura Herrero, Sylvia Hyland, Leonardo Novaes Nascimento, Ryan Pinto Ferreira, Kim J. Vicente, Carlos Alessandro Bassi Viviani and James Wear （）