The number of participants required for a pilot study depends on various factors, including the research question, the study design, and the effect size that you want to detect. Generally, pilot studies are small-scale studies conducted to test the feasibility of a full-scale study, and to estimate the effect size, variability, and recruitment rate of the study population. Regarding whether to include or exclude pilot study participants in the full-scale study, it again depends on the research question and study design. In some cases, pilot study participants may be included in the full-scale study, whereas in other cases, they may be excluded. The decision should be based on the research question, the validity and reliability of the pilot study results, and any potential biases or confounding factors.