What is widely regarded as the minimum sample size necessary for reliable research results?

The choice of 30 as the minimum sample size for reliable research results is grounded in statistical principles, particularly due to the Central Limit Theorem. This theorem states that as sample sizes increase, the sampling distribution of the sample mean will approximate a normal distribution, regardless of the population's distribution, provided the sample size is sufficiently large.

A sample size of 30 is commonly considered a threshold because it is large enough to reduce the impact of outliers and increase the reliability and validity of the estimated mean and other statistical measures. At this size, basic assumptions about the behavior of statistical tests, such as t-tests or ANOVA, start to hold true, allowing researchers to make more generalizable inferences about the larger population from which the sample was drawn.

While smaller sample sizes can sometimes yield valid results, they often come with greater variability and uncertainty, which can lead to less reliable conclusions. Therefore, the suggestion that a minimum of 30 participants is needed helps ensure that research findings are more robust and representative of the underlying population.