That should be in the title of the article. "Safety incidents at Tesla plant were 31% higher than industry average in 2015".
Without the 31% higher, you'd expect a 50-50 chance of being above or below the average. 31% higher sounds like its might be statistically significant. You'd need other numbers to be sure - e.g. if there are only 1.53 incidents on average, then Tesla might be the unlucky factory that had 2 incidents instead of 1.
Without the 31% higher, you'd expect a 50-50 chance of being above or below the average. 31% higher sounds like its might be statistically significant. You'd need other numbers to be sure - e.g. if there are only 1.53 incidents on average, then Tesla might be the unlucky factory that had 2 incidents instead of 1.