One rule of thumb we use to check for "unusual" results:
If a value is more than 2 std deviations away from the mean,
we can deem it to be unusual.
Ex. Focus groups of 12 people are randomly selected to discuss products of the Famous Company.
It is determined that the mean number (per group) who recognize the Famous brand name is 7,
and the standard deviation is 0.60.
Would it be unusual to randomly select 12 people and find that greater than
10 recognize the Famous brand name?
Ans: Use the mean-2(standard deviation) and mean+2(standard deviation) to find that
7 - 2(0.60) = 5.8
7 + 2(0.60) = 8.2
One rule of thumb we use to check for "unusual" results:
If a value is more than 2 std deviations away from the mean,
we can deem it to be unusual.
Because finding 10 people is outside your +/- two std dev cut offs,
we can say that result is unusual.