Owning pigs during the Stone Age in China was a display of wealth. Evidence for this comes from examining for this come from examining burial sites. If the skulls of sacrificed pigs tend to appear along with expensive ornaments, that suggests that the pigs, like the ornaments, signal the wealth and prestige of the person buried. A study of burials from around 3500 B. C. concluded that "there are striking differences in grave goods between burials with pig skulls and burials without them. … A test indicates that the two samples of totals artifacts are significantly different at the 0.01 level." Explain clearly why "significantly different at the 0.01 level" gives good reason to think that there really is a systematic difference between burials that contain pig skulls and those that lack them.