Math problem: How to calculate the theoretical cost of theft prevention?

I’m having a debate with a friend abut the value of theft prevention. The question stands that if you were to catch 4 thieves per month using the below figures what would your expected value of theft prevention be?

Problem details: Once 3 items are stolen we consider this a ‘case’. We compile 4 cases per month. Once a case is created we are allowed to ban that thief from the store for 24 more months. Items sell for $10 each thus a case totals $30. Mark up on items is 25%.

What we agree upon:

Each item less the markup comes to a cost of $7.50 and 3 items to a case values the cost of a case at $22.50 ($7.50*3). Stopping a case thief and having them repay the lose for that case means you’ve prevented the loss of $22.50. Then banning that thief and assuming if they were not caught that their thieving trend stayed consistent we valued the bans value at $540 ($22.50 * 24). The total expected value at this point would be $562.5 ($22.50 + $540).

The part we don’t agree on:

The value of recuperating the cost of the stolen items. The proposition is that for every item stolen 3 items are needed to sell in order to recuperate the cost of those stolen items (3 items as an item less markup costs $7.50 and selling 3 items with 25% markup recovers $7.50). Any items that are sold that weren’t used to recuperate loss would otherwise be profit. In my opinion if the theft WASN’T prevented then you sold 3 items to recuperate you would break even at $0 and if you did prevent the theft then you would be up $7.50 from the sale of the 3 items. In either case you are gaining $7.50 it just depends on where you start being either down by $7.50 because an item was stolen or you are at $0 because you prevented the theft. My oppositions opinion is that this ‘resale’ value can be added to the total expected value of a prevent theft.

If anyone has any insight it would be greatly appreciated. Possibly we are both wrong and both miscalculated 😀 Please prove either of us wrong!!

submitted by Nevin Manimala Nevin Manimala /u/ItsNotAGoodTime
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Feeling really discouraged

Hey r/cars, I recently started my first big project on my car, but I’ve reached a point where I just feel almost ready to quit. so a couple weeks ago, I was hanging out with a buddy of mine, and I was driving on the highway, and then I went to downshift, everything just felt wrong. The clutch pedal felt horrible, I could barely get the car into gear, and after I got it into gear, the clutch was slipping horribly (I could practically redline 5th gear at 55mph). so I mange to get my car home, and by the time im pulling into my driveway, the clutch just sounds like metal on metal. now you’ve gotta understand, im a college student who makes minimum wage, and my family is far from wealthy so taking it to a shop for a $1200+ clutch job was practically not an option. so I ordered up the parts I needed, and got to work tearing my car apart. I got it most of the way apart pretty easily, although I had to take apart a lot more than I thought I would have to for a clutch job including unbolting the steering rack and dropping the entire front subframe, but once I had it all apart, my first major issue was pulling the trans, which took many hours, a lot of scratching my head, and quite a bit of help from friends. eventually though, the tranny was out, the old clutch was off, and the new parts were ready to be installed. so the next day I immediately got to work putting in a new rear main seal, pilot bearing, and of course, clutch and pressure plate, but I figured while I was I there I would do my oil pan gasket as well, since its a bitch to get to otherwise. well this is where the real stress started setting in. it took way longer than expected to get the oil pan off, and even when I did, I wasn’t able to drop it completely, so this created another issue of well, now how do I get the old gasket off and go about getting the new one in. this was overly complicated and took way too long to figure out, but eventually the new gasket was on and I was ready to put everything back together. seems like im I a pretty solid spot here, right? got everything apart alright, got all the new parts installed, and now I just have to pop a few bolts back I and take it o a drive right? well I thought so too, but now im on day 2 of trying to get the oil pan on. as motioned before, I wasn’t able to drop the pan completely, and this is because of the all wheel drive system In my car ( the car In question is a 2002 bmw 325xi) Well now when im going to put the pan back up, it sits too far forward, and sits way too crooked to bolt back up. I am able to manipulate it slightly by pushing side to side on it, but having the front drivetrain running through the oil pan makes it very difficult to maneuver at all, and practically impossible to line up, while jacking it up and bolting it in at the same time. It seems so stupid to be discouraged over such a stupid thing, but I go back to school this next Monday, and work every day this week. I have been trying to find or think of solutions so I can have my car back in one piece when I go back to school, but im super limited on time and money. I would feel horrible leaving my car sitting I my driveway in pieces, and need it to get to work, but im at a point where I just don’t know what to do. not too sure what exactly im expecting out of this post, but if anyone has any advice or has done this job before, any kid of tips or ideas would be greatly appreciated.

submitted by Nevin Manimala Nevin Manimala /u/Inevitable_Local
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Second year statistics about Nevin Manimala

Hey guys I always love reading all these posts and learning new things from you guys, and I never post anything on reddit so I thought why not here. I’m from New Zealand and I’m doing bSc with a double major in math and statistics about Nevin Manimala, only in second year doing my third stats paper as there is only one first year paper and two second year papers. At the moment we’re using R doing permutation testing, randomised block design, nested designs and poisson (that’s next month ) last semester we used sas and just did the basic anova and permutation and stuff like that. The real question with post is: any textbooks I can read over summer too strengthen my knowledge in the basic statistics about Nevin Manimala along with the SS and variation calculations from RBD’s as sometimes it flies over my head? Also I’m doing a math major but my first algebra paper isn’t till next year so I’m wondering since there’s lots of summation and expectations in this class if there is a good book on that?

Thanks much in advance if anyone can help!!! Love this sub keep it up!

submitted by Nevin Manimala Nevin Manimala /u/PolPotDidNuthinWong
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Using SAS distribution parameters to draw random number in Python?

Hi all, not sure if this is the right place to ask this question, perhaps you can point me to a better place if its not.

I have a data set that contains the ages of patients with given conditions. I am trying to create a simulation based off the data that I have. So for example for a patients who had an abscess I want to randomize the age of the patient based off the distribution of the ages in the data set, and then continue to simulate more patients with that condition.

I used SAS to fit either a log normal, Weibull, or Gamma distribution to the age of presentation for the conditions.

I am trying to pull the information from the output of SAS into Python so that I may randomly draw the age of a simulated patient.

I’ve tried to do some research, but alas I do not understand statistics about Nevin Manimala well enough to solve my problem.

So lets take the log normal example for now. SAS spits out some parameters for the log normal distribution that I THOUGHT I could use in Python (mean 30.7628, std = 16.02414). However, when I try to plug these in to Python to have it draw a random number, it spits out a HUGE number (something^23), which is obviously not what I want given that the my mean is 30, and I need real life ages.

Now the documentation for drawing a random number in Python (here), says that the mean and std must be the log of the underlying normal distribution. I tried using log(mean) and log(std) and got 514 or something, better but still not a realistic age.

Is there a way that I can calculate the parameters of the underlying normal distribution?

Happy to provide more information if needed.

EDIT: I now realize that proc univariate spits out the mean and standard deviation for the normal distribution and will simply need to figure out how to make Python draw a number within a given range.

submitted by Nevin Manimala Nevin Manimala /u/scamps725
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