Following are the two methods of random sampling :
- Lottery Method : Under this method, all the units from aggregates are selected and assigned a unique number which is written on separate cards or balls and an unbiased person picks them one by one.
- By rotating a drum : In this method, circular pieces of iron or wood on which indications or numbers of the units of aggregate are written are put into a drum of circular shape and then this drum is rotated vigorously. An unbiased person takes out that number of pieces which is equal to the number of units for which sampling is to be done.
