Random walk / Montecarlo simulation

Why during a montecarlo simulation generally we take as result of the predction only the 25% quantil and the 75% quantile?

This is a montecarlo simulation (30 days) based on the price of a coin.


As you can see at the end, he only takes as ”valid” the 25% quantile and the 75% one… why ? Why does he not take the ”mean” of the final gaussian (the result of the Montecarlo simulation) as predict result of the Montecarlo?

submitted by Nevin Manimala Nevin Manimala /u/luchins
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Help Determining the Best Gambling Option

In the game Rust a recent update added a spinning wheel minigame of sorts. Seen here.

Basic mechanics of it are: you bet any amount of money on a number, if it lands on that number you get your original bet + that number times your original bet. For example, betting 10 on 20 would yield 0 if it landed on anything other than 20, but if it did land on 20, you would get 210 back,

Based on my own napkin math, betting on 3, 5, 10, and 20 all have the same return on investment, for this I just multiplied probability of each item: 1 or 4 or 6 out of 24 times its multiplier 3, 5, 10, or 20, giving .834 return each time. Assuming my math is correct, my question is if I’m going to bet on just one color (3x, 5x, 10x, or 20x) what should I bet after each loss to maintain profit assuming infinite currency.

submitted by Nevin Manimala Nevin Manimala /u/game2gaming
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Reducible Error vs Irreducible Error (Prediction Interval)

Hi everyone. So my textbook states that a Prediction Interval will always be wider than a confidence interval because it includes both reducible error and irreducible error.

Alright so let’s say I used multiple linear regression on my data and I have my model. So I compare my model estimates to the actual data points. I get all the residuals and square them, divide by N, sqrt that and I get standard error. The standard error is 5 so this means my model was off by 5 on average correct? So is this the reducible error or irreducible error and how do I find the other missing error?

submitted by Nevin Manimala Nevin Manimala /u/Futuremlb
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Beginners Practice Problems for Bayesian Statistics

Hey all. I’m a recent grad trying to learn about Bayesian Statistics. (I took stats courses throughout my education, but it was pretty much exclusively Frequentist stats). I was wondering if anyone here knew where I could get my hands on some free/cheap practice problems that someone new to this could work with using R.

submitted by Nevin Manimala Nevin Manimala /u/PJHFortyTwo
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I need to find a loop to find the probability exactly X independent events occur

i have 12 independent events occuring, and need to figure the probabilities of X number of events. This is for a sports schedule, so basically after 5 games the probability of being 0-5, 1-4, 2-3, 3-2, etc.

What would be the quickest way to calculate this with some type of loop to figure this out without manually doing all 4095 possibilities by the time I get to week 12.

submitted by Nevin Manimala Nevin Manimala /u/molodyets
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Best practice around coding responses in Stata

Hi all,

I’ve got some survey data in Stata, and one of the variables has several answers in the same cell (e.g. Answer 1/Answer 2/Answer 3). I’ve split (split var, p(“/”) each of these into different variables.

However, I now have up to 10 new variables and wanted to know the best way of coding these. I can code each of the new variables with the responses but how best should I combine these in order to do cross-tabs? Do I create binary variables for each of the 10 potential responses and then do tabs that way? E.g. tab BinaryVar Age? Thoughts very much appreciated, and please let me know if the above isn’t clear.

Thank you!

submitted by Nevin Manimala Nevin Manimala /u/thismustbeavailable
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How do you test for correlation of error terms?

Hi. Say I have my model and I plot the residuals and I think there might be a correlation in the error terms. How do I test to see how strong this correlation might be? I know there is the correlation term r which tests how strong a linear relationship is between two variables, so I could do this for the error term and my estimates, but I am not sure if this is the thing I want? Because what I want is kind of like a test of a variable with itself right? In my head what I think I want is testing if an error term will likely have some info on error terms close to it, so a correlation test isn’t right for this situation to me. Any help is appreciated, thanks!

Edit: So after thinking it over some makeshift bullshit way I came up with is if my number of observations is huge, I could plot my error terms and find the average. I could then take samples of error terms that are near the average, and find the distance between the point to the right of it and to the left of it. I do a ton of samples, and if the average is very small compared to the standard deviation, then I can confidently say the residuals are likely correlated. This seems way longer than it should, not to mention it would need a ton of observations. Is there some type of equation that tests this?

submitted by Nevin Manimala Nevin Manimala /u/Futuremlb
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SPSS: What data analysis method should I use when I want to compare how two different groups answer to “yes/no”-questions?

I am doing a study for my bachelor thesis. Two groups have read two slightly different vignettes but responded to identical survey questions. Some of these questions have a binary yes/no-format, whereas others are ordinal variables. But I do not know how to analyze the yes/no-questions. If I want to know whether there is a significant difference between how the two groups answer these questions, what analysis method should I use?

submitted by Nevin Manimala Nevin Manimala /u/TrojanNorse
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What can I say from looking at the structure of the Fisher information matrix?

I have a problem where I can easily compute the expected Fisher information matrix. An image reconstruction problem, where I estimate thousands of “parameters” (each one is a pixel)

But I can’t invert the FIM. So, what can I say from looking at its structure? Suppose My FIM is circulant. Suppose that the diagonal terms do not change,but the off diagonal terms become smaller. Can I say anything regarding the expected variance?

submitted by Nevin Manimala Nevin Manimala /u/lucaxx85
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