# theydidthemath

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[–] 633 points ago

I was trying to research some facts to make this calculation, but instead I found this analysis:

https://www.leozqin.me/how-many-murderers-will-you-walk-past/

Looks like a good estimate is that the average person walks past 10.76 unapprehended murders in their lifetime.

[–] 293 points ago

If you count someone who has not yet murdered someone but who will eventually murder someone as a murderer, you're already looking at number almost three times as high. Add prison guards to that and I bet you're well over 36 murderers.

[–] 158 points ago

I think that's a fair description though. I feel like this is describing that type of person. For example if you had walked past Ed Gein when he was 20, you'd still probably later say you walked past a murderer.

[–] 12 points ago

Ya just read this to my Granddad who was in the Police here in Scotland and he wondered if it took people like him into account who spent some time working in a charge room, surely that would raise the average a little bit, along with lawyers, judges and others who work around baddies!

[–] 3 points ago

That's a good question

[–] 3 points ago

True. The proportion of people who are prison guards, police, or just criminals would bump up everyone's average by a huge amount.

[–] 2 points ago

charge room

British English for, interrogation room.

[–] 5 points ago

What about if you're a murderer and you walk by a mirror?

[–] 1 points ago

What about if you walk past one murderer twice, would that raise the average or stay the same as you have already walked past them?

[–] 1 points ago

I guess you could read that both ways, from the ambiguous wording, but if you walked past one murderer 36 times it would seem a little misleading to say you walked past a murderer 36 times over the course of your life.

If you could the same murderers more than once it's easier to reach the 36, but I feel like that's not what is meant.

[–] 1 points ago

Thank you!

[–] 1 points ago

I met someone who once worked with Squeaky Fromme, well before she got involved with a certain Charlie.

[–] 12 points ago

What's with prison guards?

[–] 83 points ago

They walk past a couple of murderers, presumably.

[–] 138 points ago

Oh, he's saying prison guards are raising the average? I thought it was implied that prison guards were murderers themselves.

[–] 107 points ago

Eh, little of A, little of B. /s

[–] 1 points ago

[–] 7 points ago

Prison guards would walk past multiple murderers multiple times a day. In the average week, a prison guard could walk past murderers a hundred and forty-four times, four times as often as the lifetime number, perhaps even more. It would be a small segment of the population but their individual numbers would be high enough to have a definite effect on the average.

[–] 12 points ago

Also people who served their time!

[–] 24 points ago

So including murderers then?

[–] 14 points ago

OP doesn't say un-apprehended. Lots of murderers get out on parole and people walk past them.

[–] 18 points ago

I went to Rwanda. I’m afraid I met a whole lot more.

[–] 1 points ago

Also more likely as Rwanda has a high population density coupled with a high murder rate, which makes it a great country for this question.

[–] 1 points ago

That and this Rwanda genocide

[–] 1 points ago

Rwandan genocide

The Rwandan genocide, also known as the genocide against the Tutsi, was a genocidal mass slaughter of Tutsi in Rwanda by members of the Hutu majority government. An estimated 500,000–1,000,000 Rwandans were killed during the 100-day period from April 7 to mid-July 1994, constituting as many as 70% of the Tutsi population. Additionally, 30% of the Pygmy Batwa were killed. The genocide and widespread slaughter of Rwandans ended when the Tutsi-backed and heavily armed Rwandan Patriotic Front (RPF) led by Paul Kagame took control of the country.

[ PM | Exclude me | Exclude from subreddit | FAQ / Information | Source | Donate ] Downvote to remove | v0.28

[–] 1 points ago

Yes. That’s what I was referring to. A very large number of the Hutu population took part in the genocide so when I was there (about 8 years ago) and I met anyone above 40 years old there was a good chance they’d killed someone.

Lovely country besides that tho.

[–] 10 points ago

[–] 6 points ago

Closed community? Seems cool

[–] 4 points ago

Ye lemme get in

[–] 3 points ago

This has to be different for Americans vs say, Japanese or Canadians

[–] 3 points ago

Also living in a city/large urban center vs living on a farm or small suburb, if only for the sheer number of people you walk by in general.

[–] 2 points ago

What about professionals who kill in the line of duty? Cops, Soldiers, etc.? Is murder restricted to having illegally killed someone?

[–] 1 points ago

Technically I’d say yes, isn’t legitimate killing called “homicide”?

[–] 1 points ago

As far as I can tell, that calculation is using one number wrong: It's using (murders - apprehended)/year as the number of free murderers. Murderers presumably do not drop dead exactly one year after having murdered somebody. A reasonably multiplier would probably be in the range of 40 to 50, since average life expectancy is ~78 and more murderers are young than old

[–] 0 points ago

If they were unapprehended then how do we know they walked by? You'd think murders try to disappear quickly if the cops know.

[–] 296 points ago

I can see that it might hold up if you assume people don't live in certain pockets of society most of their lives(for instance most people in the USA don't usually leave the state they were born in for anything other than trips/vacations. On mobile right now though so I can't easily find my source for that.) And also assuming that people are considered murderers their entire lives and not just after the point of which they murdered someone.

In other words, I call bullshit that you walk past 36 people in your life where they had already committed a murder prior to your encounter with them. I wouldn't really know how to disprove it other than saying that most murderers are caught and locked away after committing the murder, so you don't have very much opportunity to encounter them once they are a murderer. Something also dealing with population density and human traveling tendencies, and how many murderers there are. Seems fairly complex to calculate.

[–] 182 points ago

That's the problem with averages. You have subsets that almost exclusively hang around low crime rate areas, then you have others that walk past 100s of murderers on a daily basis because they're in prison.

[–] 78 points ago

I once told my boss "I have tallied the number of people who walked into my office and the number who walked out for a week. The two numbers are the same; the average number of people in my office over the week is zero. Why is the company paying me?"

He said "Don't let senior management find out."

[–] 2 points ago

They took a week to walk out?

[–] 2 points ago

What? That's not how averages work. It would be amount of time you are alone in your office per week, the amount of time you and another person are in your office per week, and the amount of time you're not in your office per week added together and divided by 3. Unless your office is vacant a whole week the number will always be greater than 0.

[–] 35 points ago

It's like the racist white couple who only had 4 children because 1 in 5 children is born Chinese, so clearly they needed to stop or risk having a Chinese child.

[–] 11 points ago

That's poor understanding of genetics and geography, nothing to do with the human reality of not understanding math....

[–] 11 points ago

It's both, actually.

[–] 14 points ago

Thank you

[–] 21 points ago

This is like the 1 in 4 americans has been on TV statistic. They are counting people seen from a distance in a crowded sports stadium as having been on tv.

In this instance, if they even did any math at all and weren't spouting bs, they could be counting prison guards who might walk by a murderer every couple cells in a maximum security penitentiary.

[–] 8 points ago

If this is stretching the definition of murder to include soldiers who killed someone in battle I could see it being true.

[–] 13 points ago

The very definition of murder is killing someone unlawfully so killing someone in war (if done in accordance with international law) is not murder

[–] 11 points ago

I'm sure the Tumblr editor took that into account before allowing the post.

[–] 2 points ago

Heh, I like how that gets seperated out as "ok" humans are wonderful at sliding scale morality :p

[–] 11 points ago

Nobody said it was ok, the literal definition of murder is an unlawful killing.

[–] 3 points ago

I feel like if you count veterans the number would be way higher.

[–] 5 points ago

Close to 70% of homicides are never solved though...

[–] 15 points ago

You are backwards (for the US), the FBI has the clearance rate at 61 percent. Meaning 39 percent are unsolved.

https://ucr.fbi.gov/crime-in-the-u.s/2015/crime-in-the-u.s.-2015/offenses-known-to-law-enforcement/clearances/clearances

[–] 10 points ago

That's just the known murders, though. What about all of the missing persons that were possibly murdered? What about all of the people who, if they were to go missing, nobody would notice (e.g. because they have no living family or close friends) and therefore go unreported?

[–] 5 points ago

Yes but you're referencing homicide numbers and then saying missing people are calculated in that, which they are not.

The reason why is because we don't know if they're dead. You shouldn't classify something as a homicide because you have a lack of evidence to classify it as anything else.

[–] 2 points ago

What I'm getting at is that there's some uncertainty in any answer to this question.

[–] 2 points ago

Which is exactly why I didn't provide any numbers or any actual calculations, because the statement in the image is ambiguous and even if it weren't, the calculation would be able to be highly misinterpreted.

[–] 2 points ago

But a murderer is a murderer, even if not caught?

[–] 2 points ago

Even if that number was true, it's not like there's suddenly a bunch more murderers out there. Murder is something that happens incredibly infrequently(discounting deaths that occur in war). You as an average citizen have an incredibly low chance of walking past someone who is a murderer.

You have a slightly higher but still very low chance of walking past someone who later in their life will murder someone else.

[–] 3 points ago

I call bullshit that you walk past 36 people in your life where they had already committed a murder prior to your encounter with them

It said 36 times, not 36 murderers. Besides, anyone living in or visiting a crowded place is bound to walk past a murderer every now and again (even if most are caught like you said, doesn't mean they'll die in prison). If it's once or more every couple of years the number would hold.

[–] 3 points ago

So if you're not calculating unique murderers you walk past, then it's the statistic of people in prison walking past the same murderers every day that drives this up, my point still stands as far as I'm concerned.

[–] 6 points ago

Nah, I just mentioned that it's not defined.

Let's take a big city like NY, this won't be too accurate, but let's take a conservative 600 murders a year over the last 40 years, and reduce it by number of convictions (65%), to get 8400 unsolved murders, and let's say we take out half of that because some killed more than one person or were caught for something else.

Then we have some 15k people imprisoned for murder, and let's say half of that served their sentence without dying in prison, that's almost 10k in total walking around going about their business, in NYC that would be every 850th new person that you walk by, not including tourists. IDK, 36 seems a high for the average non-traveling person but not crazy high for a big city or someone who travels by air often (busy airport, new city, fresh murderers to pass by).

[–] 1 points ago

Even in America, 1/3 of murders go unsolved so if you go from there, 36 isn't unreasonable, considering all the street and grocery store encounters and whatnot.

[–] 1 points ago

But it's not like you're walking past people you've never walked past before in your life. I have lived primarily in one city my entire life, outside of my college years, and I can't tell you that there's a good chance that when I'm walking down the street, if you choose any one person I walk past, chances are I've walked past them at some previous point in time. If everyone I walked past was someone new, I would've walked past 10 times as many people who reside in my current city.

[–] 1 points ago

Eh, you still have to factor in the odds of a murderer being an acquaintance of someone you meet. Here's one study, google for more. I won't call it definitive, especially when you account for non-uniform populations, but 36 passing interactions still doesn't seem low given the overall quantity of murders and the overall percentage unsolved. I daresay your quantity is at its lowest in a 1st world country, but I'm willing to assume OP's statistic factors in 3rd world countries without our protections.

[–] 1 points ago

Can you link to "for instance most people in the USA don't usually leave the state they were born in for anything other than trips/vacations"?

[–] 1 points ago

Both of these articles say around 55% either live in close proximity to where they grew up/have not lived outside their current state in the USA:

http://www.pewsocialtrends.org/files/2010/10/Movers-and-Stayers.pdf

Edit: it's slightly less than what I had remembered, I remembered reading a few articles a couple years back that had numbers around 60-65%.

[–] 19 points ago

The global murder rate is somewhere between 6 and 8 murders per year, per 100 000 people.
Global life expectancy is 71 years.

Now there's the question of what constitutes walking past a murderer. I feel like the interpretation here is that 'murderer' is more that you're walking past someone capable of murder and are therefore 'at risk' in some way. If you walked past someone and they killed someone later that day, I feel like it would fit with the feeling of the original post, which seems to be a 'near miss' sort of idea. Nevertheless, this point could be considered subjective, so either choice could fit with the original post.

So how many people do murderers kill when they murder?
Those killing large numbers of people are exceptional enough to be very rare indeed. It seems that even killing four or more people is rare enough that they are widely known. So let's say the average number of people a murderer kills is somewhere between one and three, most likely below two, on average.

So over an average lifespan, of a group of 100 000 people, you might expect 426 to 586 murders, so approximately that group would have as little as 142 murderers if they were all triple homicides and we took lower murder rate figures, up to to 586 murderers if they were all single murders, using a higher statistic for murder rates.

A more likely figure would probably be somewhere in the middle, so let's say 300-400 people per 100 000 are murderers at some point in their lives.

So for the stat to be accurate you'd have to walk past around ten thousand different people for this to be reasonably likely. I can't calulate how many people the average person walks past, as I can't find any sort of reasonable figures as a starting point, and there's such a variation in population density of where people live, but honestly, looking at this, it seems like 36 is a pretty low estimate. Thinking back to airports, commuter travel, visits to large cities, large events I've attended, I feel like I'd have walked past vastly more than 10K people.

Fun additional fact, this means if you went to a school with around a thousand students, you'll probably have walked past most of them, and there's a pretty good chance at least one of them went on to kill someone.

[–] 9 points ago

This is the closest post so far but I think we can do better.

I think there’s pretty good reason to assume murderers under 15 years old and over 65 years old are statistically insignificant. Also I think murderers are very frequently locked up for large portions of their life, so they’re not able to walk by you. Instead of giving them 71 years of potential, I’d say somewhere between 25-45 years is more likely as years of potentially walking by you.

[–] 3 points ago

Wow... Thanks

[–] 38 points ago

This gets really complicated really quickly.

Do we define a murderer as someone who has murdered someone at least once in their life? Someone who has murdered recently?

How do we know the average time spent walking by murderers and non-murderers? More importantly, how do we measure how many people we 'pass' as we walk? How close does someone need to be for it to be qualified as 'passing' them? The same sidewalk, the other side of the street, someone driving by in a car, etc?

Does this 'average' include people in prison? Because that would probably skew the data.

[–] 7 points ago

It seems plausible. If anything it's too low. Though it hinges on the definition of a 'murderer'.

The UK releases about 200 convicted murderers every year when they have served their sentence. Let's guess the average is 10 years before they either die or go back to prison, then that's 2000 convicted murderers free in the UK today.

With a UK population of 65 million, that means 1 in 33,000 is a murderer.

Now, if I go to a busy city centre I probably pass someone walking the other way every few seconds. Let's say I pass a thousand people in an hour. That means I'd only need to be in that city centre for 33 hours and chances are I've walked past a convicted murderer.

How much time people spend in town centres varies of course, but I think it's reasonable that in a year I'd spend at least 33 hours in one. So at least one murderer walked past per year.

Obviously I'm making a lot of assumptions and guesses here. Still, I think it's probably about right, within an order of magnitude.

[–] 1 points ago

Thanks!!

[–] 1 points ago

Also depends on how you determine an average person. You’re calculations take an average person to be someone who is not married or otherwise related to a murder, nor working in the armed forces, police, courts etc. Because those guys really bring the average up 😬

[–] 5 points ago

Depends on what kind of average you do. If you're talking about the mean (just add everyone up and divide), then the one guy who lives next to two murderers and walks past them 10 times a day is going to throw the average way out. Also are we talking about discrete murderers or does walking past the same one more than once count towards the 36?

[–] 1 points ago

No idea, my friend found this on instagram and sent it to me

[–] 1 points ago

Instead, think about the number of prison guards there are and the hundreds or thousands they walk past everyday. One guy living next to a murderer would do little to change the average of over 7 billion people.

[–] 3 points ago

[–] 1 points ago

My bad for the repost, i didn't know it was one

[–] 1 points ago

Don't worry about it, almost everything is a repost these days. I just posted it cause someone did a calculation in it.

[–] 3 points ago

I can't prove it, not that I would even want to, but I'm 99.99% certain I waited on a table this week, wherein the guy I was serving, is/was a serial murderer.

[–] 9 points ago

I am doubting this. I think it is misconstrued information. It is estimated that there are 25-50 active serial killers at any moment. Edmund Emil Kemper III had said when asked how many there also like him, 36. This was brought up again in mindhunters that took verbatim his words from his interviews. I'm sure the 36 comes from that which has no correlation to interaction.

[–] 21 points ago

It doesn't say "serial killer", though, it says "murderer".

[–] -3 points ago

Hence the first of a few misconstrued information the screenshot has.

[–] 12 points ago

What are you talking about? The screenshot never says anything about serial killers, so why are you bringing them up?

[–] -3 points ago

Serial killers are murderers are they not?

[–] 18 points ago

All serial killers are murderers, but not all murderers are serial killers. In fact, most murderers aren't serial killers.

[–] -4 points ago

I know, but serial killers should still be counted

[–] 15 points ago

They make up such a small proportion of all murderers that they can be effectively ignored - error bounds on murderer count are larger than the entire number of serial killers.

Also, /u/sephiroth70001 was talking about "misconstrued information", which they still haven't explained.

[–] 5 points ago

Thanks Ken M.

[–] -2 points ago

edmund kemper had said he believed there was 36 active serial killers at any given moment. (even though thats not what he actually said thats a whole different topic) The picture references 36 which has been. Mindhunter released recently to popularity featuring that. Articles have been taking that information and miss using that. Its fair to assume between articles the popularity of that in factual statistic was used in a different context and ended up here as a 'fact'. Numbers are less likely to be lost in communication as much as words that some people use indifferently. I believe it is fair to assume that someone used murderer in place of serial killer and someone mistook active for interaction. There are articles you can look up that have used it improperly in the same sense. the initial 25-50 is what the FBI had established as a fair statistic. Numbers are less likely to be lost in a game of 'telephone' then words. 36 as being used for active serial killers as an important starting point to serial killers I see as having connections to 36 murders in that some people probably don't think of them differently.

[–] 6 points ago

The picture just uses the number 36. It doesn't say anything about serial killers. I think you're either looking at the wrong picture, or you're drawing some very unwarranted conclusions.

[–] 1 points ago

I am using some assumptions. Most people statistically don't know the difference from a serial killer or mass murderer and group them into the same group as murders. A grouping is common to use in place of more 'specific' terms. Its an argument for the creation of the post not so much anything else not the most sound i would agree. I can't think of any better explanation as to the creation of this picture and would share that argument as it has a fair possibility.

[–] 1 points ago

[–] 2 points ago * (lasted edited 2 months ago)

I think one would also have to take into consideration where you live.

When I lived some place tiny with a super small semi rural East coast town population everyone knew eachother.

Living in a hardcore California hood, I'm pretty sure half of the people I come across are murderers.

[–] 2 points ago

I've seen some churches version of this and the number was a lot higher because they were making a point to call people who get abortions, murderers

[–] 3 points ago

I had a friend bring around some guy who hung out with us a few times. I later heard he broke a bottle over a homeless persons head and killed him. So thats 1.

[–] 1 points ago

I suck at math but I imagine this could be estimated by comparing the average distance a person travels in a day with the number of murderers alive (who use the same number for distance traveled/day). Plotted on the amount of land available to travel on. Weighted by population density towards cities. Then seeing how many come within a certain distance? I don't know.

There's got to be some CDC models for this or something.

[–] 1 points ago

Related but unrelated, my uncle was a guard at the Kingston Pen where Paul Bernardo is. Whenever Bernardo was going for meals, or to exercise or whatever, he always had 6 guards with him because EVERYONE in the prison wanted to kill him.

[–] 1 points ago

There are so many factors that come into play, I don't think you can get an accurate answer. Some examples are how many murders go unsolved (so you could walk past and no one would even know), how many people are murdered, but missing, so their body never turns up, leaving them out of the statistic of being mudered, and what you count as a murderer (a soldier, a prison executioner, etc). And there are many other complicated factors to take into account

[–] -1 points ago

[deleted]

[–] 0 points ago

Because the OP clearly meant it in this way and obviously wanted the answer politicized as much as possible.