The manual discusses the main issues related to the application of the apparatus of probability theory and mathematical statistics to the study and analysis of computer algorithms. New quality assessments of computer algorithms are introduced - information sensitivity and trusting labor intensity, relevant in the design of information and software systems . The manual is illustrated with a number of examples, contains questions and tasks on the material of each chapter and can be used as a modern addition to the existing educational literature on this issue. The textbook is aimed at specialists in the field of computer science and algorithm analysis , algorithmic software developers and intended for students, Post-graduate students and teachers , Specialization in Mathematical Informatics , Development, Analysis and Research of Computer Algorithms .