5 questions0m 0s
Learn the skill
Identify who answered, how they were chosen and what they were asked. A result from a self-selected group does not automatically describe everyone.
Worked example
If 8 of 10 chess-club volunteers prefer a new chess board, the result describes those volunteers. It does not establish that 80 percent of every student prefers it.
A Bold Shoe Advertisement
In a fictional school survey, 20 running-club volunteers look at pictures of two shoe designs. Fifteen prefer the new design and five prefer the old one. No one tests the shoes while running. An advertisement later says, 'Our new shoes make every student faster!' The survey organizer keeps the original question: 'Which design do you prefer?'