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# All Questions

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### Generating random samples from a custom distribution

I am trying to generate random samples from a custom pdf using R. My pdf is: $$f_{X}(x) = \frac{3}{2} (1-x^2), 0 \le x \le 1$$ I generated uniform samples and then tried to transform it to my custom ...
7k views

### How to draw random samples from a non-parametric estimated distribution?

I have a sample of 100 points which are continuous and one-dimensional. I estimated its non-parametric density using kernel methods. How can I draw random samples from this estimated distribution?
589 views

### Estimate the size of a population being sampled by the number of repeat observations

Say I have a population of 50 million unique things, and I take 10 million samples (with replacement)... The first graph is I've attached shows how many times I sample the same "thing", which is ...
11k views

### Cluster Big Data in R and Is Sampling Relevant?

I'm new to data science and have a problem finding clusters in a data set with 200,000 rows and 50 columns in R. Since the data have both numeric and nominal variables, methods like K-means which ...
12k views

### How to resample in R without repeating permutations?

In R, if I set.seed(), and then use the sample function to randomize a list, can I guarantee I won't generate the same permutation? ie... ...
7k views

### Sampling with replacement in R randomForest

The randomForest implementation does not allow sampling beyond the number of observations, even when sampling with replacement. Why is this? Works fine: ...
1k views

2k views

### What is behind JAGS (Just Another Gibbs Sampler)?

I have been using JAGS but I am not quite sure how it actually simulates it values. I need to know in a general sense what's going on in the background.
2k views

### Downsampling excessively sampled curves

I'm looking for a quick (event if not so accurate) way to deal with over-sampled curves using R. Consider the following example in which x contains 1000 values in ...
72 views

### Is there a more efficient method for creating a probability distribution?

I have written a short function in R to estimate the expected number of mutations that will be observed in a set of DNA sequences. The parameters are the mutation rate (x), the length of the DNA ...
260 views

### How to sample from a distribution so that mean of samples equals expected value?

Given a random variable $X$, how do I have obtain $N$ random variates of $X$ so that the mean value of my samples equals the expected value of $X$? E.g. let $X$ have uniform distribution on the ...
1k views

### Sampling from empirical distribution

I have a vector of y (min is > 0, max could be 1), for which, i have no idea what distribution is. But based on the data we have, vector y, we can get the empirical cumulative probability distribution,...
750 views

### Has anyone publicly shared an implementation of RUSBoost in R?

There's no package available on CRAN, so I was hoping someone in the community had written their own function/package. I see it's been done in MATLAB, so I may just have to start with that and write ...
73 views

### Repeated catch–mark–release (urn problem)

Imagine I have a small pond with some fish in it and I want to estimate its population size. I don't have a lot of resources at hand, in fact all I do have is a fishing pole, pen and paper, and a lot ...
279 views

### Sample selection and variation in the variable of interest when using panel data

I wonder how to reason when selecting samples. I am doing a panel data regression analysis about how the euro membership correlates with the budget deficit in the member countriues. Using R that is: ...
83 views

### How to testing the probability of two factors being found together?

I know how many times a particular factors has been found: values<-cbind(f=c("S1","S10","S3","S4","S5","S6","S7","S8","S9"),count=c(9,8,4,24,20,4,8,21,5)) I ...