Systems and methods for selecting follicular units in a distribution of follicular units are provided. A selection parameter, such as a distance-related parameter separating the follicular units to be selected, may be used to determine a desired quantity of follicular units to be selected, such as a desired percentage of follicular units to be selected, and to help provide a substantially uniform distribution of selected follicular units. In addition, a characteristic parameter, such as a characteristic distance or characteristic density, may be determined. The characteristic parameter may be used in determining the desired quantity of follicular units to be selected and or may be used for treatment purposes.