When calculation of minimum sample size is not justified

We read with interest the paper of Estévez, et al, recently published in Hepatitis Monthly (1). That article was a Letter to the Editor on the study conducted by Nikui Nejad et al (2). One of the comments made by Estévez et al was on the adequacy of the size of the studied sample. They believed that the sample size was not adequate based on the provided data and the type of study (1). In the reply from the authors, a familiar mathematical equation which is frequently used for prevalence study designs was presented to explain the way the sample size was calculated in Nikui Nejad’s study (1).