Solar power is contagiousadding one rooftop system on a block increased the average number of installations within a half mile radius by 0.44.
ecause he's constantly scrutinizing his traffic to figure out why certain posts do well and others don't, Mr. Zimmerman also keeps a running list of "hot" themes in his head. "It might be that right now, people don't care about stories about cats that much, and instead, sloths are more popular," he says. "So I'll have a rule—cats are out, sloths are in, focus on sloths because that's going to be your meal ticket." The whole process happens very quickly. "Within 15 seconds, I know whether an item is going to work," Mr. Zimmerman says. He usually has a headline ready to go a few seconds after that. "It's a biological algorithm," he says. "I've put myself into the system—I've sort of become the system—so that when I see something I'm instantly thinking of how well it it's going to do." Indeed, Mr. Zimmerman says he can no longer tell the difference between stories he finds interesting and stories that will be popular. "If it's not worth posting then I'm not interested," he says.
The first person reading the comment was 32 percent more likely to give it an up vote if it had been already given a fake positive score. There was no change in the likelihood of subsequent negative votes. Over time, the comments with the artificial initial up vote ended with scores 25 percent higher than those in the control group.