 Dabalataan, iddatteessuun mit-carraa yeroo baayinni jamaa hinbeekamne yookiin tokkoo tokkoon addaan baasuufis rakkisaa tau kan fayyadamnu tauu Kumar 2005:177 akkanatti dhiheessa, Non probability sampling designs are used when the number of elements in a population is either unknown or can not be individually identified. 