It means a convenient sample is obtained by selecting convents units from the universe. Convenient sample is also known as chunk. It means a fraction of universe being investigated by convenience. For example a sample obtained from telephone directory or from the list car registrations etc. Is a convenience sample. This method is used for making pilot studies.
(1) This method suffer from bias or prejudice in selecting units from the universe
(2) Result obtained is not representative of the population and are unsatisfactory.