except that referral hiring isn't a thing almost anywhere
I know because I've referred people I KNOW are great SE's and I'm literally willing to vouch my own employment for, and they still get treated no different to any other candidate
I remember the first time I worked at a company that did referral hiring that skipped the interview process.
The first few hires were amazing. Everyone thought we had struck gold: Just find people your employees can vouch for, and hire them! Why didn't anyone else think of this?
Then we got a referral hire who turned out to be rather bad at everything, from coding to getting along with people. And another who was really entry-level, but their friend had referred them as being much more competent. Then we started screening more, and caught a referral candidate who barely knew anything about the things their friend had vouched for them having had done.
So we went back to using referrals as an additional signal, but they still had to go through the interview process.
That's the problem: Some people will only refer truly excellent candidates. Other people will just refer their friends regardless of their skills.
It very quickly becomes a "you scratch my back, I'll scratch your back" networking game, where people refer all of their friends with hopes that those friends will return the favor in the future.
Referral bonuses led to this being gamed too. Tech companies giving ~$5k out for a hired referral - people would bring in literal strangers and claimed they worked with them. There is/was even a market for referrals on blind and suchlike.
I'm not saying referral hiring is executed well. It's really poorly executed. When I look at the data of companies I've hired for and tracked the success rates of referral hires, they systematically perform better than average.
Those people pass both tests -- referral and standard hiring. To me the question hinges on whether people refer people who might fail standard screening, or if they're just cherry picking in ways your analysis "discovers."
The difference to employers might be moot I suppose, but if you want to substitute referral for standard hiring screens you kinda need to get at something like this to know if referrals are contributing any new information or just boosting hit ratios on existing tests.
The latter is the assumption most of us are making. People tend to refer people based on an intrinsic understanding that 1) I know what my friend likes and I think they will like working here and 2) I know what my employer likes and I think they will like my friend.
No2 is usually formed by a good understanding of how a company measures success in any given role. You'll find the same principle applies to good recruiters. The more a recruiter understands about how your company measures success, the more likely they are to submit candidates that will pass your interview process.
There can be an element of politics to rejecting a referral hire. Your coworker may not want you to be stacking the team with "your people". Petty and sad but it happens.
Back in the '00s, referrals were a bonus if they were able to hire the person away from their current employer. I was a referral from a person who I regularly met at the Irish pub in Mountain View (the SGI / Netapp thirsty Thursday - one was on the decline while the other was on the way up). When the $1000 went through, a round of drinks was bought for the group.
Now it seems that referrals are a "You want a referral? Like me on Linked In and I'll put your name in."
Instead of a few high quality referrals over the course of a year it is dozens of people trying to skip the first filter a month.
I've been with my current employer for 18 months. I was a referral and the person who referred me got a $15,000 bonus. I've since referred 2 people. I've gotten one bonus so far and the other should be here in ~3 months. 3 of the 5 companies I've worked for in ~20 in this industry came through my network. Anecdotes but it's worked fine for me.
The only time my referrals haven't been given immediate, obvious special treatment was when it was a referral at a large company, submitted directly to HR through some internal referral webpage. That basically guaranteed them an interview but otherwise didn't move them along. All of my other referrals have been made in-person directly to my manager (or someone up the org chart) and they have invariably been given an offer after an abbreviated interview process.
My last place of employment took my referrals and treated them like garbage, including ghosting a former VP. I asked many times why they hadn’t contacted him and they ultimately pinned the blame on their contract recruiter. Also saw multiple engineer referrals get burned by our asinine hiring process. And this was a small startup that was desperate for more people.
I've experienced the same thing in recent years. Referrals are just another way to put a resume into the ATS. I have no opportunity to actually expend any social or political capital to bring that person in. I get excluded from the hiring loop to avoid bias. I basically become a human "Apply" button.
I know because I've referred people I KNOW are great SE's and I'm literally willing to vouch my own employment for, and they still get treated no different to any other candidate