Marc DuQuesne 79 Posted March 7, 2017 Author Share Posted March 7, 2017 The best example I can come up with to illustrate the differences between European and American realities (especially western US) that CM is talking about is from a German company that decided to build spud harvesters in Idaho. They bought a local company (that I worked for at the time) and sent a bunch of their engineers over to show us how to do it right. They explained to us that their harvesters weighed less than 70% of what ours did and could harvest faster. That would of course increase production and would allow farmers to buy smaller tractors at the same time, making money while saving it. They designed a new machine and we built a prototype. It made it 34 minutes. The engineers that designed it were used to fields that had been cultivated for centuries. We plant potatoes in patches of dirt wedged between old lava flows that have been cultivated this year. They hit an average sized rock for a field in Idaho, the harvesters we'd been building for years would've bounced right over it, their machine was a total loss. Not that I think living in what could be considered a frontier compared to where most people live should have anything to do with a persons right to bear arms. It just means I have less of the really dangerous predators around. Note that Idaho is always near the bottom of list for murder and violent crime rate in the US while having some of the highest gun ownership and concealed carry rates. Link to post Share on other sites

Driver 4,539 Posted March 7, 2017 Share Posted March 7, 2017 Not that I think living in what could be considered a frontier compared to where most people live should have anything to do with a persons right to bear arms. It just means I have less of the really dangerous sexual predators around. Note that Idaho is always near the bottom of list for murder and violent crime rate in the US while having some of the highest gun ownership and concealed carry rates. fixed Link to post Share on other sites

Marc DuQuesne 79 Posted March 8, 2017 Author Share Posted March 8, 2017 Not that I think living in what could be considered a frontier compared to where most people live should have anything to do with a persons right to bear arms. It just means I have less of the really dangerous sexual predators around. Note that Idaho is always near the bottom of list for murder and violent crime rate in the US while having some of the highest gun ownership and concealed carry rates.fixedRead this the first time and couldn't find the insult, so I read it again. Still can't find it but I'm sure it's supposed to be there. Did you confuse 'less' with 'more'? Link to post Share on other sites

pavonis 937 Posted March 8, 2017 Share Posted March 8, 2017 I don't think it is insane to be concerned about a person shooting up a college campus. It does happen, and often. Did this unfortunate fellow with cue sticks get targeted by mistake, or perhaps deliberately? People have called in false threats for various reasons. I've heard of cases of students calling in threats just to cancel classes so as to avoid exams. That's insane. Legitimately fearing a possible active shooter on campus is not. It doesn't really matter if good guys are packing, either. It's not going to prevent a bad guy from taking out some innocents first. Link to post Share on other sites

Marc DuQuesne 79 Posted March 9, 2017 Author Share Posted March 9, 2017 I understand stopping the guy to ask questions if it looked funny. The problem is the panic. Why does it turn into an active shooter alert? That is the part that surprised me. This is why it surprised me, http://www.localnews8.com/news/crime-tracker/man-arrested-after-bringing-a-gun-to-a-bar-and-threatening-others/368207261 Idaho folk don't usually strike me as the type prone to panic. If they get to the point of panic, they act. Calling the police and hiding in a closet because they saw a long bag is not what I would expect, even if they aren't armed. My hunch is that it was a non-resident student that got their panties in a bunch on this one. So I researched the actual policy a little further, it appears to me that the school official on the radio interview was wrong unless there has been a change in the policy, which is possible since there was an applicable law passed since 2014 (when this policy was written). The law allows schools to set the policies on weapon carry permission. If ISU changed the policy they haven't updated their webpage. http://www2.isu.edu/policy/9000/9000-Possession-of-Firearms.pdf They have exceptions listed, like the gun show I went to, but general carry does not seem to be allowed. ****ing radio bullshit. Link to post Share on other sites

Carrie Mathison 661 Posted March 9, 2017 Share Posted March 9, 2017 I don't think it is insane to be concerned about a person shooting up a college campus. It does happen, and often.?? Since 2014, there have been 8 shootings on a college campus. Not all of those would be considered somebody "shooting up" a college, but I'll go ahead and include all of them to give you the maximum number. There are (according to the US Ed Dept), 3,026 four-year colleges in the US. I'm gonna go ahead and leave out 2 year community colleges, to give you the maximum benefit of the doubt here. Given roughly, a 180 day school year (the average, again according to the Ed Dept).... the chances on any given day that you'd encounter a school shooting are: 0.000734% Not sure in what universe this would be considered..... "often." Link to post Share on other sites

pavonis 937 Posted March 9, 2017 Share Posted March 9, 2017 Thank you for some numbers. What's your source? Your reference is a bit vague. I'm not certain you treated the probability calculation properly; I would use a Bayesian approach myself. I wonder what the rate of false threats are, too. Perhaps I should've just said "too often". Link to post Share on other sites

Carrie Mathison 661 Posted March 9, 2017 Share Posted March 9, 2017 Thank you for some numbers. What's your source? Your reference is a bit vague. I'm not certain you treated the probability calculation properly; I would use a Bayesian approach myself. I wonder what the rate of false threats are, too. Perhaps I should've just said "too often".https://nces.ed.gov/fastfacts/display.asp?id=84https://nces.ed.gov/surveys/sass/tables/sass0708_035_s1s.asp I wikied the number of shootings. May be off by one or two, but it wouldn't change the % by any significant amount. I'm not certain I treated it correctly either, but I suspect I'm in the ballpark. The last time I took a math class was AP Calc BC, like 15 years ago, so feel free to re-calculate and mock me as need be. Yeah, if you had said "too often," I probably wouldn't have noticed and not said anything. Not sure it would help your point though. The probability of even encountering a school shooting, much less actually being injured in one, is so statistically improbable, that to actively be concerned about it..... I actually would say it's insane. Or at least so profoundly irrational, that I cannot comprehend it. You have as good of a chance as winning Powerball. In fact, that might be more likely. Link to post Share on other sites

pavonis 937 Posted March 9, 2017 Share Posted March 9, 2017 The odds of winning the Powerball are 0.0000003422%, making getting shot in a school attack (by your calculations) about 2000 times more probable than getting all 5 numbers and the Powerball.Living life constantly in fear of an attack, at school or work (for some of us those are the same thing), might be irrational, but an intelligent person once saidPeople in general are pretty irrational and also notoriously bad at long-term planning.I doubt even a Bayesian approach would significantly change the resulting probability, certainly no more than an order-of-magnitude either way (though till I run the numbers, I could be wrong). I'm certain no one here is interested in a long post about conditional probability. Link to post Share on other sites

Jacen123 1,955 Posted March 10, 2017 Share Posted March 10, 2017 A Bayesian approach could certainly change the probability by many orders of magnitude if the prior distribution on the probability is heavily concentrated near 1. I'm not saying it would be a good estimate, but therein lies the "joys" of Bayesian methods. Link to post Share on other sites

Carrie Mathison 661 Posted March 10, 2017 Share Posted March 10, 2017 hahaha pav... alright. Powerball is less likely. I obviously did pull that out of my ass, but you got the point. And good use of my own words against me- but that doesn't make it any more sane, now does it? I actually would be interested in a long post about conditional probability. This is not something I would consider myself smart on, and I like learning new things. Of course, one person's enjoyment is not really worth your effort, but I'm just sayin. Link to post Share on other sites

Marc DuQuesne 79 Posted March 10, 2017 Author Share Posted March 10, 2017 164 Powerball jackpot winners from 2003 - Feb 2016. http://portalseven.com/lottery/powerball_jackpot_winners.jsp 141 killed in school shootings from Columbine (Apr 99) to Feb 2016. https://www.google.com/amp/abcnews.go.com/amp/US/school-shootings-columbine-numbers/story%3Fid%3D36833245 Something wrong with your odds. Powerball isn't the only lottery. Link to post Share on other sites

Cerina 3,018 Posted March 10, 2017 Share Posted March 10, 2017 You guys take pedantry to a whole new level I swear. Link to post Share on other sites

pavonis 937 Posted March 10, 2017 Share Posted March 10, 2017 164 Powerball jackpot winners from 2003 - Feb 2016. http://portalseven.com/lottery/powerball_jackpot_winners.jsp 141 killed in school shootings from Columbine (Apr 99) to Feb 2016. https://www.google.com/amp/abcnews.go.com/amp/US/school-shootings-columbine-numbers/story%3Fid%3D36833245 Something wrong with your odds. Powerball isn't the only lottery.I think there are a lot more people playing Powerball than people at risk of being attacked at a school. I'd estimate that there are easily 10 million tickets in play for Powerball for any given drawing, and it undoubtedly goes much higher as the jackpot grows larger (we all know someone who only plays when the jackpot gets above their threshold value). I cited the odds of winning the Powerball jackpot as reported on the Powerball website. If you have an issue with those numbers, take it up with them. The risk of getting attacked on a school campus on any given day is very low. But, once someone is spotted who looks suspicious (whatever that may mean to someone), the odds change because the conditions have changed. It's not "what are the odds of an attack today?" but "What are the odds that this individual, carrying a suspicious package, is a threat?" General possibilities for this situation: A real threat is identified as a threat (true positive)A real non-threat is identified as a non-threat (true negative)A real non-threat is identified as a threat (false positive)A real threat is identified as a non-threat (false negative)The false negative is the worst case outcome in this situation, and ideally is reduced to as close to zero as possible through appropriate methods. Since the odds of true positives (individual shooting up the school is correctly identified) and true negatives (regular student really is going about doing regular student stuff) are hopefully high (close to 1), the only way to reduce the rate of false negatives to as close to zero as possible is to raise the rate of false positives and reduce the rate of true negatives, which manifests as being overly cautious. The ultimate manifestation of a high rate of false positives is putting metal detectors and x-ray scanners at every entrance to a facility because it treats everyone as a potential threat. It's not feasible at a university to secure all the entrances to the grounds this way, so the next best thing is for people who are suspicious of a person to call the authorities to investigate (following the edict "if you see something, say something"). So let's try Bayes theorem, P(X|Y) = P(Y|X) P(X)/P(Y) whereP(X|Y) is the probability of event X given condition YP(X) is the probability of X in generalP(Y) is the probability of Y in generalP(Y|X) is the probability of condition Y given event X Let Y: carrying suspicious package that may be gunsLet X: attack The relevant question "what are the odds that this individual, carrying a suspicious package, is a threat?" can be framed as P(attack | suspicious package) = P(suspicious package | attack) P(attack)/P(suspicious package) To calculate the odds, we need numbers for P(Y|X), P(X) and P(Y). At a guess, P(Y|X), the probability of someone carrying a suspicious package that may have been guns now that an attack is underway, is probably high, but I don't have any numbers for that. Not everyone who attacks a school necessarily walked in with a package that would've been identified as suspicious. P(X) is hopefully low, since most schools don't experience an attack on most days. I don't know the numbers for P(Y) either, but if it is low then the conditional probability P(X|Y) actually goes up. Jacen, if you're still reading this, I'd appreciate your thoughts. Of course there are other ways to approach the calculation; these are just my first thoughts on the matter. I haven't actually started digging for the numbers yet, and I don't expect it to be quick work since it's not pressing. Link to post Share on other sites

Cerina 3,018 Posted March 10, 2017 Share Posted March 10, 2017 I see I was wrong... Link to post Share on other sites

pavonis 937 Posted March 10, 2017 Share Posted March 10, 2017 I thought you appreciated science and math. Here's a real-life application of math in a socially and politically relevant issue. Link to post Share on other sites

captainbleh 164 Posted March 10, 2017 Share Posted March 10, 2017 Yeah, conditional probability is fun (even though I don't understand it to the point of feeling confident enough to do my own tables) and often counter intuitive, so seeing a working for this situation is interesting. It's not that relevant because the probability of being attacked at a US educational institution is still very low, but there's no harm in knowing that working out the probability of a lottery win is really easy and that working out of the probability of other things can be a bit challenging Link to post Share on other sites

Marc DuQuesne 79 Posted March 11, 2017 Author Share Posted March 11, 2017 164 Powerball jackpot winners from 2003 - Feb 2016. http://portalseven.com/lottery/powerball_jackpot_winners.jsp 141 killed in school shootings from Columbine (Apr 99) to Feb 2016. https://www.google.com/amp/abcnews.go.com/amp/US/school-shootings-columbine-numbers/story%3Fid%3D36833245 Something wrong with your odds. Powerball isn't the only lottery. I think there are a lot more people playing Powerball than people at risk of being attacked at a school. I'd estimate that there are easily 10 million tickets in play for Powerball for any given drawing Over 70 million students in the US (not even looking at staff) are sold tickets for the school shooting 5 days a week. Still more lottery winners. Link to post Share on other sites

pavonis 937 Posted March 11, 2017 Share Posted March 11, 2017 What do you want me to say? The Powerball odds are what they are. Are you suggesting the odds of a school shooting are comparable to the Powerball odds? Maybe they are. I haven't made any of the calculations presented here, you know. All I did was compare Carrie's calculated odds to the official Powerball odds. Its irritating to be blamed for alleged miscalculations I didn't perform in the first place. Link to post Share on other sites

Marc DuQuesne 79 Posted March 11, 2017 Author Share Posted March 11, 2017 I never said you calculated the odds wrong. I said there was something wrong with the odds. If you didn't calculate them then don't take offense. I just didn't want this thread to die with that fuzzy math being accepted as accurate. Link to post Share on other sites

pavonis 937 Posted March 11, 2017 Share Posted March 11, 2017 You keep quoting me in regards to your claim there's something wrong with the odds. Please stop doing that. Link to post Share on other sites

Jacen123 1,955 Posted March 11, 2017 Share Posted March 11, 2017 I'm exhausted after a week full of explaining related, though simpler, concepts to a bunch of students this week, so I will hold off in depth comments about pavonis's previous post until a bit later, but I will mention a few things. First, a few years back when the Powerball jackpot got so big, I calculated the probability of winning it because of a lot of local interest and I got the same probability that the Powerball website gave, so I assume that they haven't changed their website if the Powerball rules haven't changed, so I feel very confident that it is correct. Secondly, pavonis is definitely correct that conditional probability is important to consider here because people typically make various assumptions when casually talking about probabilities, but don't explicitly state these assumptions, so end up talking about very different scenarios. Thirdly, as has been said already, both winning the Powerball and getting attacked in a school shooting are extremely rare events. As such, we need to think about where the probabilities of these events are coming from. The provided probability for winning the Powerball is calculated directly via counting techniques and the laws of probability, so assuming that each number actually is equally likely to be chosen, it is the probability of that event occurring, given that you play exactly one ticket. On the other hand, due to the nature of the random process, itself, any reasonable value given for the probability of getting attacked in a school shooting will be based substantially on collected data (though, there could be some subjectivity introduced if a Bayesian approach is used). As a result, this probability is actually just an estimate. Because it is so rare to observe, the number of repetitions of the random process of observing whether you get shot by a gunman at school that are needed to get a reasonable estimate are astronomical. Even the time span of 18 years provided by Marc's figure is likely not enough to get a great estimate. Fourth, at the risk of sounding pedantic, we really do need to be very specific about the words we use. For instance, odds are considerably different than probabilities. Probabilities are bounded between 0 and 1. Odds, on the other hand, are unbounded above. If p is the probability of an event occurring, then the odds of that event occurring are p/(1 - p). An even more important distinction is in how we actually define the event of interest because I think that this is obscuring things even more here. Again, the probability provided by Powerball is for a you to win the jackpot on a given day while playing one ticket. Even if we make the unrealistic assumption that each person who plays on a given day plays only one ticket, the probability of someone winning the jackpot is considerably higher. A classic example of this seemingly contradictory phenomenon is sometimes known as the birthday problem. Suppose that you are in a class of n students. If we make the assumption that each birthdate is equally likely (which isn't 100% correct, but is pretty valid based on data), then let's first think about the probability that you share a birthday with someone else. Suppose that there are 50 people in the class. Then, it turns out that the probability that nobody else shares your birthday is 0.8742, which means that the probability that at least one other person has your birthday is 0.1258. However, for reasons outlined here, the probability that nobody in the class shares a birthday is only around .03, which means that the probability that at least two people in the class share a birthday is approximately 0.97, which a result that surprises many people because of the way we typically play fast and loose with how we define the events we are interested in. Trying to determine probabilities for school shootings faces the same problem, but magnified. For instance, are we talking about the probability that you, a single person, are attacked in a school shooting at a given school on a given day or are we talking about the probability that anyone is attacked in a school shooting anywhere in the country during a given time interval? The difference between those two events is tremendous, but both of these situations might be used honestly by people thinking about this issue, which might lead them to come to very different conclusions about just how likely it is to get attacked in a school shooting. So much for keeping this short, but I am sure I could find much more to say about this issue from a purely probabilistic perspective, leaving aside my own feelings on the matter. Link to post Share on other sites

Marc DuQuesne 79 Posted March 11, 2017 Author Share Posted March 11, 2017 You keep quoting me in regards to your claim there's something wrong with the odds. Please stop doing that.I've quoted you twice in this thread (including this time). The post about something being wrong with the odds didn't quote anyone, not my fault you chose to defend them. Link to post Share on other sites

Carrie Mathison 661 Posted March 11, 2017 Share Posted March 11, 2017 Pavonis- Interesting post, but one comment. You mentioned that the number of people playing Powerball is greater- well, let's assume that is true (I'm not sure it actually is... how many millions of children are attending school on any given day?), but let's assume it's true. It shouldn't matter in terms of the win probability, right? I mean, your odds are based entirely on numbers chosen, which is entirely within your own independent control, and the sheer number of people changing would not impact your own independent chances of selecting the correct numbers. Zero people could play or 100 billion, and it shouldn't matter. Now the number playing would be very important for determining the probability that you'd have to share the jackpot. Now contrast to school shootings. Could it be that the number of people attending on any given day (and the number of schools, etc.), actually would influence your chances of a particular incident? In other words, that as the number goes down, your chances of an encounter go up? This is assuming (a BIG if, I know), that the number of people that are potential shooting threats per school is relatively constant, and that the number doesn't proportionally increase relative to the student body as it increases. It has occurred to me that , then, my probability calculation is not really a probability, but just the number of incidents per X school days. Perhaps too crude to be useful. Or perhaps, it really is more like Powerball- that there is an independent trial per school- let's say, similar to the chances of choosing the correct number, there is an independent calculation made that any given school will experience a shooting that day. And then the numbers of schools that day and students attending are really only relevant in determining the odds that two or more shootings happen on the same day. Link to post Share on other sites

Carrie Mathison 661 Posted March 11, 2017 Share Posted March 11, 2017 Jacen- fascinating. First, I want to go ahead and take credit for the fact that this is... I think.... the first time I've ever seen you long post. Second, I found that intriguing and I'm glad you took the time to write it out. Third, if you have much more to say, I'd love to hear it. Fourth, I honestly hadn't considered the difference when I first wrote about it, but I was talking about a single person ("you") encountering. It occurs to me now, that this difference could be pretty important. I think we'd have to be talking about the single person encountering, since the original impetus behind the discussion was the rationality of one person making a false positive. Link to post Share on other sites

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