“Among those who run, rich candidates are also more likely to win.

“And what we show is that rich candidates are more likely to raise early money. In particular, they’re more likely to raise large-dollar donations, which then have a greater return in subsequent quarters.

“However, many, many candidates supplement with their own money. Something like 40 percent of non-incumbent general election winners self-fund at least $10,000. I think people don’t really understand the prevalence of self-funding a

“So I’ve learned that fully self-funded candidates, meaning those who don’t supplement with financial support from others, typically lose. Self-funding on its own is not as valuable as getting money from others, and in particular large-dollar donations from others.

“The bulk of my research is looking at US House primaries, and I think you could probably draw similar conclusions for Senate primaries, except that in most cases, Senate primaries have way more information. So in the case of Michigan, I think people knew largely what the choices were. And after you get to that stage, largely through money and advertising and voter outreach, and campaigning, after that point, money might matter less because voters become more familiar with choices. But this is a really steep hurdle in most congressional primaries.

“And that’s not going to mean that if you raise a lot of money, you definitely will win. That’s never been the case and that’s still not the case. But it does matter for you, it matters for who is seen to be seriously in the mix, who is perceived to be relevant. And in this cycle, just like in most cycles, virtually all contenders who are either successful or are seen as successful show support through early fundraising.

“In many ways the argument of my book is not very groundbreaking if you talk to practitioners, but it hasn’t been empirically documented in the ways that I did. Some other people in political science call attention to endorsements. The other theory is that money matters not as a signal of viability but for material goods — so to buy advertisements, office infrastructure, hiring staff, and consultants.

“I think that people forget how low information these contests usually are. Many primary voters really don’t know much about candidates. I think in the Michigan Senate example, that was less true. Money isn’t irrelevant, but when you have other pieces of information, that can override money. And furthermore, in that case, both of the candidates were spending millions of dollars in the primary. I mean, this is just so unique in a lot of ways.