I am just a hobbyist, but as i understand it, 5.0 sigma is just the probability of the result being bogus. So 5 sigma is very high probability, something like one in 1.4 million. i.e. the chances of the result being wrong is one in 1.4 mil. 4.9 sigma will mean lesser probability, but i am not sure by exactly how much will that 1.4 mil number reduce.