sample size


I am working on a study investigating emotional dysregulation in healthy volunteers. My aim is to propose a survey - screening questionnaire - DERS - Difficulties in Emotional Reglation Scale to a sufficient number of people and afterwards categorise the subjects into two extreme groups: (1) high emotional dysregulation and (2) low emotional dysregulation.

How should I calculate my sample size? how many people should I include in my experiments, after the screening? And how many responses should I attend from the survey, in order to be able to generalize my results to the general population?

Thank you in advance,