Both experiment groups said the signal detected by the LHC had a statistical significance of 5 sigma, meaning there's only a 5-in-10 million chance the signal was due to background processes rather than a new particle.
The Atlas group is reporting further analysis has raised the statistical significance of their Higgs signal to nearly 6 sigma, which puts the chance of the signal they observed being due to background processes down to 2 in a billion.
