In a study involving 130 people, the researchers found that 28 percent of the people who knew and were trusted by the study's participants could guess the correct answers to the participant's secret questions. Even people not trusted by the participant still had a 17 percent chance of guessing the correct answer to a secret question.
The least-secure questions are simple ones whose answers can be guessed with no existing knowledge of the subject, the researchers say. For example, the answers to the questions "What is your favorite town?" and "What is your favorite sports team?" were relatively easy for participants to guess. All told, 30 percent and 57 percent of the correct answers, respectively, appeared in the top-five list of guesses.
A bug in the code is worth two in the documentation.