The sample size formula is different for Discrete (Categorical) and Continuous (Numerical) Data.
Discrete or Categorical data can take on one of a limited, and usually fixed, number of possible values.
Examples : Yes/No, Day of the week, Month, Gender, etc.
Continuous or Numeric data is a number that can be measured on a continuum or scale and can be sub divided to more decimals.
Examples : Time, length, weight, etc.
Select this based on the type of data being analyzed