Page "Extrasensory perception" Paragraph 5

In all such experiments order of the cards must be random so that hits are not obtained through systematic biases or prior knowledge.

At first the cards were shuffled by hand, then by machine.

Later, random number tables were used, nowadays, computers.

An advantage of ESP cards is that statistics can easily be applied to determine whether the number of hits obtained is higher than would be expected by chance.

Rhine used ordinary people as subjects and claimed that, on average, they did significantly better than chance expectation.

Later he used dice to test for psychokinesis and also claimed results that were better than chance.