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This has got to be the biggest hiring fallacy I've ever heard. "It's better to reject a good candidate than hire a bad candidate."

That's completely false, and anyone who says that is completely ignorant of Bayesian logic.

Here are some simple numbers.

Suppose that a "good" candidate is a 1-in-100 find. Suppose that a "bad" candidate has a 1% chance of tricking you into hiring them anyway.

Every time you pass on a "good" candidate, that is greater opportunity for a "bad" candidate to trick you into hiring them!

Counterintuitively, if you pass on too many of the "good" candidates, in your overzealousness to reject bad candidates, you're actually INCREASING THE ODDS OF A BAD HIRE.

This is management porn. "It's better to reject a good candidate than hire a bad candidate." It makes the manager feel good. "Wow! That candidate seemed smart, but I rejected him anyway! I'm such a great leader! I make the tough decisions!"

tl;dr summary

Because "good" candidates are rare, every time you pass on a good candidate that increases your odds of making a bad hire! This is simple Bayesian reasoning!



Those are simple numbers, but they don't get at the real issue. People say that because 1 bad hire can have negative effects on the whole team, causing others to get less done and leave. Missing a good hire doesn't poison your team.


But 1 bad hire is easily correctable - you fire the person. You won't know that you missed on the good hires.

I personally have worked with several awesome people that have interviewed with Google, and none of them got hired. They all said the interview process was flat out insulting.

Interestingly enough, most of them ended up at Facebook.


>>But 1 bad hire is easily correctable - you fire the person.

Not sure if you have ever been a manager, because firing someone is NEVER easy. It hurts everyone emotionally. The person getting fired feels awful. The person doing the firing feels awful (unless they are a real sociopath). And team morale tends to take a big hit.

Here is my stance: if you hire someone who isn't a good fit, unless they actively deceived you, it is your god damn job to find a way to make it work. As a principle you should treat people with respect and dignity, and not as easily disposable and replaceable cogs.


> it is your god damn job to find a way to make it work.

No, it isn't. This is why probation periods exist. If you hired someone and they aren't working out, then at the end of the probation period you don't keep them on.

Trying to force someone who doesn't fit the team dynamic to stay is going to hurt your org. It doesn't make you a "good" manager to say to everyone "I know this sucks but deal with it because letting them go would mean I was wrong."

> As a principle you should treat people with respect and dignity, and not as easily disposable and replaceable cogs.

Which is ironic because so many job descriptions I see today are basically written as "we want to hire someone with exactly these skills, who requires zero training, and can become an expert in our systems in their first week."

No one is that way, unless your system consists of pressing one button all day, but then the job description would probably require that the person have intricate knowledge of the button and is friends with the engineer who designed it so they know what to do if the button suddenly stops working.

If companies actually treated people with respect and dignity, I'd get the training I need to become a better employee, instead of going to management and begging them for any training every 6 months like the industry is now.

/rant


> Trying to force someone who doesn't fit the team dynamic to stay is going to hurt your org.

Doesn't this rather presume that your "team dynamic" is actually good to start with?

Let's say you had a team of not very good engineers. Then you hired quite a good engineer who looked at all the terrible practices (e.g. no version control, shitty or nonexistent testing, poor build processes) and said to themselves "look, I need to fix this shit or I'm leaving, and I've got ten better offers in my inbox".

They might not be a very good team fit, but that's because the team is filled with idiots who haven't figured out how to use version control or whatever.

So, you know, the best thing to do is to get rid of them for not being a culture fit or for not being good for the team dynamic...?


> They might not be a very good team fit, but that's because the team is filled with idiots who haven't figured out how to use version control or whatever.

Yes, if you have a team like this and you hire someone who has a higher standard, there is going to be some friction between them and the existing team members. Letting that person go isn't your concern, because as you said yourself:

> and said to themselves "look, I need to fix this shit or I'm leaving, and I've got ten better offers in my inbox".

I've been in that situation before. I was hired to a company and when I got there I found out that every single day they were fighting fires because of stupid decisions management made with little foresight into how it would affect the team. Funny enough none of this was mentioned during the interview, although it was a definite red flag that they had high churn for this particular position.

I stayed there for my probation period trying to fix things so the team would fire fight every day and change management's mentality, but it wasn't happening, so I gave notice and went somewhere better.

> So, you know, the best thing to do is to get rid of them for not being a culture fit or for not being good for the team dynamic...?

No, you took me too literally. Obviously if you've got someone who has friction with the team, but they're a hard working individual who is trying to make your team better and more efficient, you should try to work through those stressful periods because in the long run it will be better for your team's health and the company's health. If some of your low performers leave during this period, that's okay, they were only going to hurt you in the long run. That being said, don't burn bridges with your existing employees. Try to find a happy middle ground that results in a better work environment for everyone.


I have been a manager, and I have had to fire people.

I have also quit a job because they fired the wrong person.

In my opinion, if you fire someone and the reaction from the whole team isn't "thank god, that guy needed to go", then you made a mistake firing them and should have tried to make it work. In the past when I fired someone, the general reaction was much more along the lines of "what took you so long". In both cases I was the one at the table defending the person while everyone else said they needed to go.

Interestingly, in both cases the reason for firing them was that the person in question was not treating other people with respect. So what is worse, letting one person shit on your whole team and make everyone else feel bad, or getting that person off your team?

Managing isn't easy.


"it is your god damn job to find a way to make it work"

That attitude is how bloat happens. There is a middle ground here. Not firing bad employees also hurts many people emotionally as does an underperforming, overbloated company. Employees are as replaceable as employers. To use a sports analogy, it's the big leagues and you may not make the team and often times it is hard to know whether someone can make the team without a trial. I believe these draconian interview practices and contract-to-hire approaches are a direct result of the never-fire-bad-employees attitude.


If Google didn't apply the equivalent of the Hogwarts Hat to placing its employees, I'd agree with you. But in doing so, they remove the ability of the potential Googler to meet their potential teammates and decide whether it's a good fit.

Ergo they own the problem, not so much the Noogler. Also generalists == mediocre code in my experience because there's no passion for such work in a lot of people who are fantastic with other in-demand skills, but I digress.

And when I joined, Google wasn't so much bloating as it was metastasizing. Most of the people I knew who joined around the same time have long since left. In contrast, I've been at the same gig ever since I left Google. The Google experience was the outlier.


Hmm. When I joined Google, I interviewed the managers of both teams I was offered a position on, and a team member on the one I ultimately decided to join.

I'm not sure if this is the norm--I believe it differs for industry hires versus those fresh out of school--but it's certainly not true that, as a rule, you can never meet potential teammates.


Two decades in the valley has taught me that you can't decide anything in a half hour conversation beyond recognizing an absolute bozo incarnate. You need to meet the whole team and preferably have lunch with them and figure out whether it's the right next step. What Google does instead reeks of magical thinking to me.

Because for the most part, Googlers aren't bozos (although a couple of the true believers in the Googleplex blew my mind with how crufty their skills and knowledge had become), but that doesn't rule out one of the many great engineers there promoted to their managerial level of incompetence. And that's what I had - a guy with no people skills whatsoever - and two teams with a total of 20+ engineers to "manage."


I agree with you, but it's still easier to fire someone than to un-not-hire someone ;-)


The good and bad the op is talking about is different. If the attitude is not the best, you don't hire anyway.

If the candidate cannot invert a binary tree and gets mostly there, and has demonstrable real world software, it's a different thing.


> invert a binary tree

What does that even mean? Swap left-right child nodes? Write it linearly (n-th children at 2n and 2n+1) and reverse it as if it was a string? OP later described it as "to min-max the tree, ascending to descending." confusing me further.


>People say that because 1 bad hire can have negative effects on the whole team, causing others to get less done and leave. Missing a good hire doesn't poison your team.

That doesn't disprove what he said. In fact it strengthens it and makes missing a good hire even worse, because, as he said missing good hires -> MORE change of bad hires (that can "poison your team").

In other words, it's not a choice: "I'm better of rejecting a good hire than getting a bad one, because a bad one could poison the team".

By rejecting good ones, who're actually getting MORE bad ones. So it should be corrected to:

"I'm better of NOT rejecting good hires, or else I'll get more bad hires and poison my team".


This is akin to banning food because people might get a stomach ache, and this is bad for the team.


> Counterintuitively, if you pass on too many of the "good" candidates, in your overzealousness to reject bad candidates, you're actually INCREASING THE ODDS OF A BAD HIRE.

Yes, but what hiring managers are doing isn't passing over candidates that they know are good, they're passing over candidates that they're not very sure about.

> Because "good" candidates are rare, every time you pass on a good candidate that increases your odds of making a bad hire! This is simple Bayesian reasoning!

Similarly, of course this is true, but again hiring managers aren't passing up candidates that they know to be good, they're passing up on candidates that they're not sure about, whom the acknowledge could be good.

Under certain conditions, every time you pass on a candidate you're not sure about, you decrease your chance of making a bad hire. The conditions are that increasing hiring standards must weed out more bad candidates than good candidates.

Let's work with your model. Suppose 1% of candidates coming for an interview are good and 99% are bad.

Hiring strategy A manages to hire all good candidates it interviews, and 1% of the bad candidates it interviews. End result: for every 100 people you interview, you get 1 good candidate and 1 bad candidate.

Hiring strategy B is more conservative and hires 50% of all good candidates it interviews, and 0.1% of the bad candidates it interviews. End result: for every 100 people you interview, you get 0.5 good candidates and 0.1 bad candidates.

The claim is something like, the team produced by strategy B is better than the team produced by strategy A, even though team B has less good candidates than team B.


The slogan represents the opposite. You hire only 10% of the good candidates but the odds of hiring a bad candidate are cut to only 0.5%.


I agree with you that if hiring strategy B led to hiring 10% of the good candidates and cut the odds of hiring the bad candidate to 0.5%, compared to 100% and 1% for hiring strategy A, then strategy B is worse than strategy A. However

1) This means that by raising your hiring bar (adopting B instead of A), you eliminate more good candidates than bad candidates. You now have to prove this empirical claim. 2) All I wanted to say was that the statements you made like "every time you pass on a good candidate that increases your odds of making a bad hire!" is only true under certain conditions (namely that raising hiring standards eliminates more good candidates than bad candidates), and it's not "simple bayesian reasoning".


The original slogan "It is better to reject a good candidate than hire a bad candidate." specifically says to make that fallacy.

As long as good candidates are rare, and bad candidates have a small-but-nonzero chance of tricking you into hiring them, it's very expensive to pass on a good candidate.

Even if you pass on 50% of the good candidates (no matter how many bad ones trick you), you're doubling the amount of time you're spending interviewing.

The only way to be sure about how many "good" candidates your are missing is to hire some random percentage of the people who fail your interview. Only a large tech company would have the resources to do that, and I'm not sure if it would be ethical, or even get the employer in legal trouble.

NO employer knows how many good candidates they miss out on, which makes this analysis very difficult.

Also, I question the ability of most employers to evaluate employees AFTER they are hired, so any analysis of post-interview performance might just be reinforcing whatever biases are present.

Also, candidates fall into THREE groups: great, mediocre, and toxic. The catch is that the toxic ones are most likely to trick you into thinking they're great. That makes it even more expensive to pass on a good candidate.


> As long as good candidates are rare, and bad candidates have a small-but-nonzero chance of tricking you into hiring them, it's very expensive to pass on a good candidate.

Yes, I agree with you. My point is that even taking this into account, even after taking into account all the other costs you mention into account, it might still be better to pass on candidates you're not sure about.

> The original slogan "It is better to reject a good candidate than hire a bad candidate." specifically says to make that fallacy.

So going by the slogan, even if passing on too many good candidates increases your odds of a bad hire (say from 50% to 80%), it's still better than hiring a bad candidate, since if you hire a bad candidate, the odds that you made a bad hire is 100%!

My interpretation of the slogan seems different from yours, mine is something like: if you hire a good person the value of your business will increase by X, if you hire a bad person the value of your business will decrease by Y, and Y is much greater than X.


This is not about numbers.

A bad hire can easily cause more friction than if nobody was hired at all. Net effect for the business is negative. You're also probably severely overestimating the likelihood of a bad hire going through.


Bad hires can be fired. Bad rejections poison the well for hiring the good candidates who never apply because of hearing about all the bad rejections.


Bad hires can be fired.

But the cost and other effects of doing so vary significantly depending on where you are. Most of the US may have at-will employment, but much of the rest of the world does not.


But the US is the place where the "It's better to reject a good candidate than hire a bad candidate" mantra comes from! European companies practice it, but they do it because they're forced to, and they don't preach it like a gospel. The US does it without any need to do it, and thinks they're gaining some sort of advantage in the process.


You can fire a bad hire. You can't hire someone you already rejected because a few weeks later they already have a job.


Easier said than done.

We had a really bad hire about 2 years ago. So bad it caused us to review our entire hiring process to understand how he got in. It took almost a year before he was fired (and he was a contractor so it should have been easier). In that time, he used up untold resources while we tried to find work he could actually do, people helping him "just in case he just needed a helping hand" and so on. Finally after wasting other people's time for 9 months, a manager made the decision to get him out.

A year later I got an email from him asking for a recommendation. Nothing ventured, nothing gained I guess.


Here I see the same logic that caused the TSA. Some rare and bad event happens, and people rush to rebuild the whole system to never let that happen again. Not even considering maybe accepting that rare and bad events happen and dealing with them more efficiently would be better? Maybe rebuild actually doesn't even prevent bad events, just specific type of bad event that already happened and is unlikely to repeat anytime soon? Maybe dealing with imperfection is better than trying to be perfect every time?

I.e., I don't know your particular situation, so I wouldn't dare to assume the reaction was wrong, but too often "we much at all costs make sure it never happens again" overwhelms any attempt at reasonable approach and cost/benefit analysis completely. Maybe getting one bad apple in occasionally is a reasonable price for quickly and efficiently hiring a lot of good people?


The mistake was simply not getting rid of that guy faster. Not that he was hired in the first place.


"Finally after wasting other people's time for 9 months, a manager made the decision to get him out."

Why did the manager wait so long?


Because it's hard to fire someone. Lets discount the emotional cost completely and simply look at this in terms of financial risk to the company.

Employee X is hired. After a month it becomes clear to the whole team that X is a bad hire. But how do you turn a subjectively obvious feeling into an objectively obvious reason to fire. Because if that person decides to sue the company after getting fired that's what you will have to demonstrate.

Just imagine how hard it is to quantify what makes someone good at our job? Code Quality? Team dynamic? These are really fuzzy metrics.

You could document how many times the engineer affected production badly and how much that cost the company. But to be realistic even great engineers do that. Heck I touched production at Google and decreased revenue by millions of dollars and it was expected that this happens. So you'd have to let him affect the company enough times to be obvious He's worse than your other engineers.

You are going to have to have documented enough clear failures to do the job to justify starting the process of firing. If you don't have a performance improvement plan then you might be able to speed up the process a little. However not having a performance improvement plan is both a bad idea and, I would imagine (IANAL etc.), could cause problems later on down the road in a potential suit.

Taken in that light 9 months doesn't seem that long at all.


In the US you do not have to prove that person was not qualified.

It is "at will employment".

There is no need to prove that employee is causing losses.

It's the employee who has to constantly "prove" to employer that this employee's salary is justified.


In theory this is true. In reality you will probably need said proof to prevent questions of discrimination of some sort.


That's why you have a probation period where it's all worked into the equation that you might be let go after three months if it's not working out.


Doesn't understand bayesian logic! Doesn't understand risk management!


Idiot: We don't want to make any bad hires! Therefore, we reject a lot of good candidates!

FSK: If you pass on many good candidates, and you have a small chance of hiring any given bad candidate, then each good candidate you reject actually INCREASES your odds of making a bad hire.

Idiot: We made a bad hire once! Never again! Now we reject lots of good candidates to avoid that repeat disaster!

FSK: But, if you want to minimize your bad hire rate, you also have to minimize the number of good candidates you reject.

Idiot: NO! NO! NO! The way you make sure you hire no bad candidates is to be so strict that you reject lots of good ones! That's what everyone told me so it must be right!

In one ear and out the other. Why do people who don't understand statistics get to be managers? If you don't understand this statistics argument I made, you're unqualified to work in any sort of technical area.


It's actually fairly reasonable. The manager doesn't want to avoid hiring bad candidates. The manager wants to avoid being blamed for hiring bad candidates. They want to be able to say "I looked really really hard for reasons why Bob was a bad hire, and didn't find any, so you can't blame me for Bob being a bad hire."

Whether or not this actually reduces the number of bad hires is beside the point. It's a classic principle-agent problem.


You're missing something vital here. They're not rejecting good candidates because they're good candidates, they're rejecting them because they're not sure enough that they're good candidates.

They fear they might be bad candidates. They'd rather reject too many than too few, so they make sure they reject everybody who they're not 100% is a good candidate. That means they may reject some good candidates that aren't easily identified as such, but it doesn't increase their chance of hiring a bad candidate; it decreases it.


Strictly speaking, I think raising the standards also could lower the probability of a bad hire (depends on the model - is bad hire completely random? does it depend on some parameter that is controlled?) together with a probability of a good hire, so I'm not sure it is a robust argument that raising standards always raises chance of a bad hire. I'd be happy to see a more rigorous proof (I know it's complete waste of time but for some people it's fun).


On a side note, this kind of passive-aggressive comment is not very welcome here on HN. Let's please keep discussion civil.


Basing all of your management decisions purely on statistics is a bad strategy. You're assuming that the weighting of good vs. bad candidate is the same, when they're not.

Hiring a good employee is not nearly as impactful as hiring a bad one. If you can have a strategy that filters out 100% of bad employees, but unfortunately also filters out 90% of good employees, this is preferable to filtering only 50% of good employees, but also only filtering 90% of bad employees. You may have more good employees with the latter strategy, but the bad employees can kill the team.


People have an irrational belief in their ability to tell the difference. This is how one gets such flawed thinking in the first place (regarding priors and probability distributions).

Firms are hierarchy-based entities. "Technical Merit" is about a third or fourth order away from what really drives the hiring decision. Its also very imperfect predictor of actual performance.

The issues is that companies use the term all the time. They want people to believe they were hired for their merit, but merit is almost always 'fit' and not technical in nature. The technical hoops are just a CYA for when the 'fit' doesn't work out (mis-judgement) and they need something to point to as to that is not arbitrary in nature to explain how other people were not hired instead.


Not really. The population is large enough that you're treating each potential hire as a random variable. Given the amount of possible good new hires the effect of passing on one actual good hire has negligible effect on the next potential hire.

The theory behind the "raise the bar" argument is that obviously good hires are easy to spot (this is the part most people reasonably take issue with), so people who do not pass that bar of "obviously good" aren't worth taking a risk on. The conclusion is statistically reasonable if you accept the premise (which, again, you probably shouldn't).


> The population is large enough that you're treating each potential hire as a random variable.

This is only true for new grads. The population of engineers with ten years of appropriate corporate experience (that match the technology survivor bias) and at the ~12 locations google can use is tiny.

When I look at my old corporation, only 3 people (of 500+ I would be aware of) were hired by google. One of them is genuinely great, but I doubt he passed the current process as a blind hire. The other two I wouldn't want to work with, but I bet they passed this process precisely because the right kind of focus. (I.e. everything people around them didn't know was their priority and since we normally focus on what's important to completing our project, none of that was so important..)

I was very interested in google when I was under the impression that (without experiencing menlo park on a daily basis,) I could either walk away with over $500k (gross) in 2- years, enjoy working there for 5 years, and/or work with the best >experienced< engineers in our field. When glassdoor and my own linkedin network revealed my best perspective into their setup, blind applying to them is now just a good filter to test my new age employability skills. So, now they've built themselves a new problem of true positive false positives who are just along for the ride.

The hiring market is already NP Hard for both sides when you are genuinely trying to get a good enough fit for yourself rather than the best deal on the market. If you try to misuse the other side they will see less ethical constraints in using the resources you'll have to put in.

How many developers genuinely want a job they can't do that they will have to be awkwardly fired from in six months and explain at every future interview?


The difficult thing with hiring bad candidates vs not hiring bad candidates is that you get to experience the bad hire every single day, so it is quite apparent that you made a mistake. With not hiring a good candidate, you don't really know what you were missing. You may just assume that the best applicant you reject is no better than your average employee. But there is a chance that that person would bring something to the table so unexpected that you can't even imagine the world that would have been had you hired them.


Obligatory reference to tptacek's post at http://sockpuppet.org/blog/2015/03/06/the-hiring-post/ -- see the end of chapter 2 for an amazing example


Apparently you hadn't been recruiting anyone in Europe. Once you've hired a bad candidate, it is very hard to get rid of it (borderline impossible in Scandinavia, for example).


You're conclusion rests on the numbers you start with, those aren't a given.


I understand your point, and I'm not trying to be a troll.

Humans are more complex than that. I don't think you can assume that candidates will perform the same all the time. Sometimes an excellent candidate can perform badly for multiple reasons (e.g. nervousness, poor preparation, bad interviewer, personal problems, etc).

It seems to me, that rejecting a good candidate, and have him/her interview again after some time, if that candidate was a 'good-hire', then it would increase the chance of hiring him/her, since it is most likely they will prepare better, and know what to expect.


Why would anyone who has a job waste a vacation day to interview at a place that previously rejected him?

If your flawed process rejected a good candidate the first time around, what makes you think the same flawed process won't reject them a second time?


And why don't they count the cost of good candidates who simply drop out of their hiring pool entirely, because they can't be arsed to bone up on the easily gamed idiotic hiring process?

I'd never even apply to Google based on the stories I've heard, and I'm sure there are plenty of others in the same position who are even better at what they do than I am. There are just so many stories out there of how crappy the hiring process is that everyone who's any good must have heard about it. Some significant fraction will have said, "Yep, not for me."


I've heard that it's not uncommon to have to interview twice before getting in to Google.


Of course, people hired after their second interview are more likely to be mediocre, because people with more options are more likely to not re-interview (like mxcl https://twitter.com/mxcl/status/608687283869503488)




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