Document Type : Research Paper

Author

• Mostafa Rastgar Agah

assessment and evaluation, psychology and educational sciences department, Allame Tabatabai' university, Tehran, Iran

Abstract

Sample size in qualitative studies is related to theoretical saturation. Theoretical saturation means that the researcher continues sampling and collecting data until he or she encounters a new insight and concept. But the number of interviews and the claim of achieving a saturated subject has always been controversial, and not every claim to achieve theoretical saturation can be considered correct. This is important because it wastes more time and money than interviews, and eliminates interviews that require less research validity. There are various methods to solve this problem, such as recommendations based on experience and thumb calculations, but the interest in a more objective criterion based on statistics has attracted the attention of experts. In this paper, two statistical approaches to determine the sample size are examined. One of these methods estimates the sample size in qualitative studies a posteriori and the other method a priori. These two methods will be reviewed, explained and finally compared.

Keywords

• Theoretical saturation
• Sample Size
• Sampling
• Qualitative research
• Research method