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This wasn't an interview, it was a test. I had a similar experience with a startup. I was interviewing for a Marketing Communications Manager position. Essentia

This wasn't an interview, it was a test. I had a similar experience with a startup. I was interviewing for a Marketing Communications Manager position. Essentially PR. One of the unofficial interviewers (at 24 year old MIT engineer working as an email marketer) challenged me with the question "How many barbers are in San Francisco?" We proceeded to map it out the analytical process on the whiteboard. He wanted to see formulas to understand how I would arrive at the answer. It was a stupid, impossible question. In a similar way to this girl's experience, he jabbed repeatedly critiquing my logic. He wrote me later to explain that he posed the same question to his girlfriend, an MIT engineer herself, and she couldn't come up with an answer. Neither could he. They offered me the job and I declined solely based on this guy and his misguided, silly behavior. I would have hated to work with him. When a company misguidedly challenges potential employees in this way it hurts the quality of its hires. Sure, Google can afford to be picky but does it really need an engineer in a Product Marketing role? Perhaps for dev-facing apps but such an interview process is overall misguided and immature.

andreyf 17y ago
Maybe you forgot to mention it, but how did you go from "discussing an intentionally impossible problem" to "misguided, silly behavior"? If your ego makes it upsetting to work with people who "jab repeatedly, critiquing [your] logic", or find it upsetting not being able to answer a question, that says quite a lot about what kind of work environment you'd be a good fit for.
- diN0bot 17y ago
  mmmmm....yes and no. if you perceives critique negatively, that's a problem with your attitude. you'll never find a good place to work because you'll react poorly to natural differences and disagreements. if others are aggressive or negative that's a problem with them, especially if they're not interested in self-analyzing and learning to be mindful. we don't know the situation in this case.
zaidf 17y ago
I disagree. I actually think the questions in both your example and google's was good in seeing how you approach a problem. The point is not the answer. It is the approach. I can think back to meetings where questions of similar nature have popped up. You have guys that want the precise numbers and refuse to make any assumption of any sort. You have guys that throw stupid guesses and just want to move forward. You have guys that do a little bit of thinking to come to a quick but critically thought out answer. This seems like a good way to identify which category you fall in and whether your approach is a good fit for the job.
anigbrowl 17y ago
I don't think this is such a terrible thing, although clearly this adversarial approach to testing ideas isn't for you, or everyone. Enrico Fermi used to challenge grad students with similar questions, the famous example being 'how many piano tuners in Chicago?'. I don't think it's a stupid or impossible question, but one that seeks to establish how you go about estimating tricky things and thus identifying fruitful territory for more rigorous research. Let's walk through it, with the awareness that we're trying to refine our techniques of estimation rather than caring about the actual number of barbers. 'Barber' implies haircuts for men. This is good, because the number of hairstylists that cater to women depends on fashion, which is hard to quantify. On the other hand, hair cutting is more related to hair growth. There's about 3/4 of a million people in San Francisco. Roughly half of them are men, so we have 375,000 potential customers. Most men wear their hair short, off the ears. Of course some wear their hair long and have it cut very infrequently, while others like it much shorter, eg with a buzz cut and have it cut more often...but some of them may cut their own hair, since a buzz-cut isn't too challenging. I'm going to assume the number of hippies cancels out the number of close-cutters because San Francisco has a bit of a hippy reputation. So much for hairstyling. OK, so I've postulated 375,000 men who average out to a 'regular hairstyle'. And I've postulated that a regular hairstyle means not having your ears covered, ie the old 'short back and sides'. While it's growing, you could comb it out of the way or let it cover the tops of your ears, but once it gets half-way down then you're either growing it out or it's time to visit the barber. How much hair is that? My ears are about 2 inches high, but I have small ears. 3 inches sounds pretty big though...I'll guess the average is 2.5 inches, so half of that is 1.25 inches. That's already pretty fluffy though...let's round it down to 1 inch. OK, so 375,000 men get a haircut whenever their hair has grown by more than an inch. How long does that take? Hair grows at about 4 inches a year, so let's say 3 months. Which gives us 1.5 million male haircuts a year for the whole city. (we could have started calling the population p and the rate of hair growth g[h] and so on, but why bother, it's a chain of reasoning we're concerned with here). A haircut takes, what, 20 minutes? it could be faster, then again some want a more difficult style. So let's guess that there's half a million hours of actual hair cutting (including the bit with the sheet and the sweeping up etc) going on in a year in SF. Now we're getting somewhere. How much does a barber work? I'd say 45 hours a week. Some barbershops open early for the business crowd, but then they're closed on Saturdays. Monday-Saturday seems reasonable, as does 2 weeks' holiday. So one barber could spend a maximum of 2500 hours per year cutting hair. Only, that seems a bit high. Sometimes you wait in line, but I don't usually think of barbers as busy flat-out most of the time. 30 hours of cutting and 15 hours a week of of waiting for a customer seems more realistic. So 1500 hours of haircutting per barber (edit: 1650, but who cares). And dividing that into half a million hours of cuttable male hair per year gives me 333, the number of people needed to cut all that hair. At this point you can start arguing about whether someone that caters to both men and women is truly a barber, or whether women can be said to be barbers even if they only cut men's hair. If your answers to those questions are no and no, and we go with the stereotype of a barber as a man who only cuts other men's hair, then I'd halve these numbers and guess that the number of 'pure' barbers in SF is 75-100. OK, so this is 10 minutes of my life I won't get back, but if I was going to market something specific to barbers then I now have a decent guess at the number of potential customers in my local metro area. Of course, you could have just said 'pass me a copy of the Yellow Pages and I'll tell you'. So having done the above, I went and looked that up and got 131 results at http://www.superpages.com/yellowpages/C-Barbers/S-CA/T-San+Francisco/ http://www.superpages.com/yellowpages/C-Barbers/S-CA/T-San+F... ...with 2 or 3 cutters at each shop, that would suggest somewhere in the 3-400 range, but some of these entries are for Salons and some are in Daly city or Sausalito, not quite in San Francisco. Still not definitive, but not too far off either. Sure, there's a lot of guessing and hand-waving here...but the important thing is that I arrived at an estimate that roughly correlates with reality. In this case I was able to check that reality (by looking up the number of self-identified barbering businesses) but once you become adept at this technique you can use it for anything, and then get on with solving the problem instead of feeling stuck by a lack of information.
ephermata 17y ago
The "how many X are in Y" is also known as a "case study question." From what I understand it's a standard practice in interviews for consulting companies, such as Bain or McKinsey. I've never seen one in an interview, but friends of mine who took that route obsessed over them. As your interviewer said, these questions are asked just to see how you will come up with an answer. The actual number hardly matters, so long as you can sell it to the interviewer. Pushing you is part of the process, as well, to see how you hold up "under pressure." If you want to be uncharitable, this is much like what a management consultant does -- come in, get some problem from a troubled company ("How can we improve sales by 20% in six months?"), develop a strategy, and then convince the client that they should do it. The interview technique makes sense for that context because it selects for people who can pull this off. Actually, for a PR role I don't think this question is such a bad fit. You will have to think quickly on your feet, answer hostile people, and come up with diplomatic, plausible answers to crazy questions ("why does your product not work with Slackware?"). The precise answer is of course important, since if you're wrong you will be caught, but how you react is more important.
DaniFong 17y ago
Isn't the sizing of markets something of marketers need to do, all day long? You can't blow $20k for a Gartner report every time you imagine a new market. You need to be able to make some ballpark estimates. These 'stupid impossible questions' have a long history. http://en.wikipedia.org/wiki/Fermi_problem http://en.wikipedia.org/wiki/Fermi_problem (Barbers cut the hair of half the population (the male half) around every two months. The population of San Francisco is about 750k. A haircut takes about 30 minutes, and about 50% of the time a barber is cutting hair. This gives about 8 cuts per day, or about 60x8 = 480 haircuts per every two months. So to service 750k/2 of the population you need about 750k / (2 x 480)) = about 781 barbers. Or roughly one out of a thousand people is a barber.)

andreyf 17y ago

Maybe you forgot to mention it, but how did you go from "discussing an intentionally impossible problem" to "misguided, silly behavior"? If your ego makes it upsetting to work with people who "jab repeatedly, critiquing [your] logic", or find it upsetting not being able to answer a question, that says quite a lot about what kind of work environment you'd be a good fit for.

diN0bot 17y ago
mmmmm....yes and no. if you perceives critique negatively, that's a problem with your attitude. you'll never find a good place to work because you'll react poorly to natural differences and disagreements. if others are aggressive or negative that's a problem with them, especially if they're not interested in self-analyzing and learning to be mindful. we don't know the situation in this case.

zaidf 17y ago

I disagree. I actually think the questions in both your example and google's was good in seeing how you approach a problem. The point is not the answer. It is the approach. I can think back to meetings where questions of similar nature have popped up. You have guys that want the precise numbers and refuse to make any assumption of any sort. You have guys that throw stupid guesses and just want to move forward. You have guys that do a little bit of thinking to come to a quick but critically thought out answer. This seems like a good way to identify which category you fall in and whether your approach is a good fit for the job.

anigbrowl 17y ago

I don't think this is such a terrible thing, although clearly this adversarial approach to testing ideas isn't for you, or everyone. Enrico Fermi used to challenge grad students with similar questions, the famous example being 'how many piano tuners in Chicago?'. I don't think it's a stupid or impossible question, but one that seeks to establish how you go about estimating tricky things and thus identifying fruitful territory for more rigorous research. Let's walk through it, with the awareness that we're trying to refine our techniques of estimation rather than caring about the actual number of barbers. 'Barber' implies haircuts for men. This is good, because the number of hairstylists that cater to women depends on fashion, which is hard to quantify. On the other hand, hair cutting is more related to hair growth. There's about 3/4 of a million people in San Francisco. Roughly half of them are men, so we have 375,000 potential customers. Most men wear their hair short, off the ears. Of course some wear their hair long and have it cut very infrequently, while others like it much shorter, eg with a buzz cut and have it cut more often...but some of them may cut their own hair, since a buzz-cut isn't too challenging. I'm going to assume the number of hippies cancels out the number of close-cutters because San Francisco has a bit of a hippy reputation. So much for hairstyling. OK, so I've postulated 375,000 men who average out to a 'regular hairstyle'. And I've postulated that a regular hairstyle means not having your ears covered, ie the old 'short back and sides'. While it's growing, you could comb it out of the way or let it cover the tops of your ears, but once it gets half-way down then you're either growing it out or it's time to visit the barber. How much hair is that? My ears are about 2 inches high, but I have small ears. 3 inches sounds pretty big though...I'll guess the average is 2.5 inches, so half of that is 1.25 inches. That's already pretty fluffy though...let's round it down to 1 inch. OK, so 375,000 men get a haircut whenever their hair has grown by more than an inch. How long does that take? Hair grows at about 4 inches a year, so let's say 3 months. Which gives us 1.5 million male haircuts a year for the whole city. (we could have started calling the population p and the rate of hair growth g[h] and so on, but why bother, it's a chain of reasoning we're concerned with here). A haircut takes, what, 20 minutes? it could be faster, then again some want a more difficult style. So let's guess that there's half a million hours of actual hair cutting (including the bit with the sheet and the sweeping up etc) going on in a year in SF. Now we're getting somewhere. How much does a barber work? I'd say 45 hours a week. Some barbershops open early for the business crowd, but then they're closed on Saturdays. Monday-Saturday seems reasonable, as does 2 weeks' holiday. So one barber could spend a maximum of 2500 hours per year cutting hair. Only, that seems a bit high. Sometimes you wait in line, but I don't usually think of barbers as busy flat-out most of the time. 30 hours of cutting and 15 hours a week of of waiting for a customer seems more realistic. So 1500 hours of haircutting per barber (edit: 1650, but who cares). And dividing that into half a million hours of cuttable male hair per year gives me 333, the number of people needed to cut all that hair. At this point you can start arguing about whether someone that caters to both men and women is truly a barber, or whether women can be said to be barbers even if they only cut men's hair. If your answers to those questions are no and no, and we go with the stereotype of a barber as a man who only cuts other men's hair, then I'd halve these numbers and guess that the number of 'pure' barbers in SF is 75-100. OK, so this is 10 minutes of my life I won't get back, but if I was going to market something specific to barbers then I now have a decent guess at the number of potential customers in my local metro area. Of course, you could have just said 'pass me a copy of the Yellow Pages and I'll tell you'. So having done the above, I went and looked that up and got 131 results at http://www.superpages.com/yellowpages/C-Barbers/S-CA/T-San+Francisco/ http://www.superpages.com/yellowpages/C-Barbers/S-CA/T-San+F... ...with 2 or 3 cutters at each shop, that would suggest somewhere in the 3-400 range, but some of these entries are for Salons and some are in Daly city or Sausalito, not quite in San Francisco. Still not definitive, but not too far off either. Sure, there's a lot of guessing and hand-waving here...but the important thing is that I arrived at an estimate that roughly correlates with reality. In this case I was able to check that reality (by looking up the number of self-identified barbering businesses) but once you become adept at this technique you can use it for anything, and then get on with solving the problem instead of feeling stuck by a lack of information.

ephermata 17y ago

The "how many X are in Y" is also known as a "case study question." From what I understand it's a standard practice in interviews for consulting companies, such as Bain or McKinsey. I've never seen one in an interview, but friends of mine who took that route obsessed over them. As your interviewer said, these questions are asked just to see how you will come up with an answer. The actual number hardly matters, so long as you can sell it to the interviewer. Pushing you is part of the process, as well, to see how you hold up "under pressure." If you want to be uncharitable, this is much like what a management consultant does -- come in, get some problem from a troubled company ("How can we improve sales by 20% in six months?"), develop a strategy, and then convince the client that they should do it. The interview technique makes sense for that context because it selects for people who can pull this off. Actually, for a PR role I don't think this question is such a bad fit. You will have to think quickly on your feet, answer hostile people, and come up with diplomatic, plausible answers to crazy questions ("why does your product not work with Slackware?"). The precise answer is of course important, since if you're wrong you will be caught, but how you react is more important.

DaniFong 17y ago

Isn't the sizing of markets something of marketers need to do, all day long? You can't blow $20k for a Gartner report every time you imagine a new market. You need to be able to make some ballpark estimates. These 'stupid impossible questions' have a long history. http://en.wikipedia.org/wiki/Fermi_problem http://en.wikipedia.org/wiki/Fermi_problem (Barbers cut the hair of half the population (the male half) around every two months. The population of San Francisco is about 750k. A haircut takes about 30 minutes, and about 50% of the time a barber is cutting hair. This gives about 8 cuts per day, or about 60x8 = 480 haircuts per every two months. So to service 750k/2 of the population you need about 750k / (2 x 480)) = about 781 barbers. Or roughly one out of a thousand people is a barber.)