Manual

Table Of Contents
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20
X will have been set to a random selection of either A or B. Listen critically, switching
between A, B and X; when you think you have identified X as either A or B, leave the
selection on the identified A or B, and press CHOOSE. This will increment the number of
test cycles but not display whether your choice was correct. The act of pressing CHOOSE
also randomly re-allocates either A or B to X. For a thorough and statistically significant test,
repeat this audition and CHOOSE cycle up to 20 or 25 times.
When you have completed a satisfactory number of cycles, press REVEAL, which will show
the percentage number of correct guesses:
A 95% confidence level is regarded as statistically significant (so anything less than that
means you have not reliably been able to distinguish between A and B — see above!). Note
that a 95% confidence level is NOT the same as a 95% correct score! (Think of a single
cycle; you might by chance guess correctly, and obtain a score of 100%, but with a
confidence level of only 50%.)
As a quick guide, for a 95% confidence level you need a minimum of 8 correct guesses from
10 cycles (80%), 11 from 15 (73%), 14 from 20 (70%), or 17 from 25 (68%).