Selecting a sample manually (raffle tickets)

  1. Write the names (or other identification) of all population members on identical pieces of paper,
  2. Mix them thoroughly in a box
  3. Select n pieces of paper (with or without replacement).

This method is rarely used in research applications.

Selecting a sample with random numbers

To select a random sample without replacement using random numbers,

  1. Number all population members, starting from index 0.
  2. Generate a random index between 0 and the largest population index.
  3. If sampling without replacement and the generated index has already been selected, go back to step 2 and select another index.
  4. Add the selected population member to the sample, then repeat steps 2. and 3. until a large enough sample has been selected.

Random number between 0 and k

The easiest way to generate a random number between 0 and 357 is to use a spreadsheet such as Excel — it has a function designed for this purpose, "=RANDBETWEEN(0, 357)". A computer-generated random value is strictly called a pseudo-random number.

If a computer is not available, a sequence of random digits can be generated:

  • Roll a 10-sided die several times.
  • In a printed book of random digits, start at a random position in a random page, then use a sequence of digits starting from there.

A random number that is equally likely to have any value between 0 and 357 can be found by repeatedly generating 3-digit numbers (between 0 and 999) until a value between 0 and 357 is obtained.