Overall, the data generated by citizen scientists are pretty good, according to David Delaney, a graduate student in evolutionary biology at McGill University in Montreal. And he would know. While studying introduced and native crabs along the Atlantic Coast from New Jersey to Maine, Delaney compared the identifications that a thousand volunteers made of crabs caught at 50 sites with those he made himself. The overwhelming majority of citizen scientists nearly always identified the crabs correctly. Even seventh graders got them right 95 percent of the time. Perhaps more surprising, third graders were right 80 percent of the time, an acceptable accuracy rate for most ecological studies. Such information is important to wildlife biologists and land managers who track the expansion of exotic species and develop programs to control them. “The only thing worse than not having data is inaccurate data,” he says.