Objective. To evaluate the procedures used to determine the population and the sample in research works carried out to obtain a master's degree at the Universidad César Vallejo, Huancayo. Methods. The research was of basic type, descriptive level and simple descriptive design. The sample consisted of 202 research papers with a quantitative approach that were analyzed with the evaluation form of population and sample criteria designed for the study. Results. 100% of the studies used non-probabilistic sampling, did not present a theoretical population, did not consider inclusion and exclusion criteria, and considered the sample size inadequately. The 97.5 % of the studies with quantitative variables did not specify the type and technique of sampling and 42.5 % of the studies with qualitative variables did so inadequately. Conclusions. The procedures used to determine the population and sa...