The larger the sample size, the more reliable survey findings are. A survey based on 500 people is more reliable than one based on 50. We therefore automatically highlights when a survey (or a group in a survey e.g 18-24 year olds) is based on a small or extremely small sample size. Small and extremely small sample sizes are based on the following definitions:
Small sample size: under 50 respondents
Extremely small sample size: under 30 respondents