Tagged Questions
2
votes
1answer
65 views
The sample size applied to a non-normal distribution
I have a single variable that represents my population values (sample of data):
...
0
votes
1answer
55 views
Determining butterfly weight distribution
I'm a researcher studying a specific butterfly species. I've conducted an experiment where I measure the weight of this species at different locations on the earth. The data is cateogorical and ...
0
votes
1answer
46 views
What is the Cauchy meta distribution?
I overhead a professor speak about the Cauchy meta-distribution, but I am unable to find anything about it on the web. My question is what is the Cauchy meta distribution and what is the theory behind ...
0
votes
1answer
104 views
R: Density estimation vs Histogram Estimation
To draw random samples from a custom distribution, I recall reading that KDE's are better than histograms. (See hadley's comment here.)
When I experimented in R, I am finding that the KDE method ...
0
votes
0answers
36 views
Comment on this method of sampling from any distribution?
Say I have a distribution, either described by a probability density function that is integrable and continuous, or by a set of discrete probabilities over a finite set of symbols.
I want to ...
0
votes
1answer
48 views
How can you find the probability that an element is part of a sampled set?
(I'm a bit of a newbie, so pardon me if I use incorrect terminology.)
Let's say I have a set of scalar values V that I sampled from a set S. I want to test whether a given value X could be a member ...
2
votes
3answers
2k views
How does the sampling distribution of sample means approximate the population mean?
I am trying to learn statistics because I find that it is so prevalent that it prohibits me from learning somethings if I don't understand it properly. I am having trouble understanding this notion of ...
5
votes
2answers
160 views
Distribution of ratio of sample means from two independent normal variables?
The Question
We have a sample of size $N$ with mean $\bar{x}$ and SD $\bar{\sigma_x}$ from a random variable $X \sim \mathcal{N} (\mu, \sigma^2)$
We have a sample of size $M$ with mean $\bar{y}$ and ...
1
vote
0answers
30 views
Sampling distributions help with questions [duplicate]
Possible Duplicate:
Probability of mean of random sample being in a certain range
When a pizza restaurant’s delivery process is operating effectively, pizzas are delivered in an average of ...
1
vote
0answers
21 views
Sample/Filter nonuniformly distributed values so that result follows a uniform distribution
I have a dataset with a nonuniform distribution. I want to sample it so that the result is uniformly distributed. If I know the class of the example, with what probability should I choose it to get a ...
4
votes
3answers
322 views
Practical difference between “sampling” and “re-sampling with replacement”
What is the difference between "sampling" and "re-sampling with replacement" from a practical point of view (I mean how do I code that) ?
When one say: "sampling $\tilde{x}_t^{(i)}$ from $p(x_t | ...
2
votes
1answer
126 views
How to sample from the product of a Gaussian and an inverse-Wishart distribution?
How do I sample from a distribution that is the product of a gaussian and an inverse-wishart distribution? I was going to use inverse transform sampling but a friend said that he thinks there is a ...
2
votes
2answers
87 views
Finding the probability of getting a complete set from N classes of objects in M draws [duplicate]
Possible Duplicate:
What is the probability of n people from a list of m people being in a random selection of x people from a list of y people?
Let's say we have 5 kinds of marbles, 1000 ...
2
votes
1answer
224 views
Something like Central Limit Theorem for variance and maybe even for covariance?
CLT states in short, that sum/mean of random iid variables from almost any distribution approaches normal distribution.
I failed to find information about asymptotic behavior of sample variance when ...
1
vote
1answer
858 views
How can I calculate cut-off points from a normal distribution?
I'm trying to calculate the upper percentage points for the 0.99 percentile for samples drawn from a normal distribution, with a sample size of 500. How can I calculate the expected values for ...
4
votes
3answers
207 views
How to sample natural numbers, such that the sum is equal to a constant?
Say I have $N$ items that are partitioned / clustered and I want to randomly repartition these items, such that the distribution of sizes of the clusters is 'similar' to those that I already have. I'm ...
3
votes
1answer
131 views
How to calculate the “unfairness” for repeated random selection?
Assume there are 16 people in a group, and each day 11 people are randomly selected from the group. Over a year, some people will be selected more times than other people.
The question is, assume the ...
0
votes
2answers
109 views
Combining expert estimates
I am trying to work on a process to improve how how well my team estimates. I want to look at using some statistics to help out and embrace the uncertainty in how we estimate tasks.
If I have a group ...
3
votes
1answer
175 views
Prior of multivariate Polya distribution?
Anyone knows a prior (preferably conjugate) to the
multivariate Polya distribution?
I need it for Gibbs sampling. So if anyone has another idea, I am interested.
4
votes
1answer
179 views
Learning to create samples from an unknown distribution
I am interested in new generating samples to approximate some unknown distribution X, where each new sample is a real-valued vector.
The purpose it to be able to create a new (arbitrary large) ...
2
votes
0answers
225 views
Distribution of the size of overlap between two random samples with duplicates?
Similar to this question, I want to know if the overlap between two samples is significant. However, my items are not unique; I have c distinct colors of items, there are mi items of color i (1 < ...
4
votes
3answers
250 views
How can I simulate census microdata for small areas using a 1% microdata sample at a large scale and aggregate statistics at the small area scale?
I would like to perform an individual-level multivariate analysis at small levels of geographic aggregation (Australian census collection districts). Clearly, the census isn't available at these ...
0
votes
0answers
82 views
Quantifying the error of an approximate probability distribution
I will approximate a given probability distribution $P$ over $\mathbb{R}^n$ with a distribution $\tilde{P}$ which is simpler to represent. I would like to keep track of the error that I'm making ...
1
vote
0answers
204 views
Lower bound for tail of hypergeometric distribution
There are several simple and widely used upper bounds on the tail of the hypergeometric distribution, including $P(X > E[X]+tn) <= e^{-2t^{2}n}$, where X is hypergeometric with parameters N, M, ...
2
votes
2answers
199 views
What is the most computationally efficient way to sample from an unnormalized density?
EDIT: After doing some more research, it seems slice sampling could be the way to go. I've seen it mentioned a lot in the context of how to sample the univariate distributions required for Gibbs ...
2
votes
2answers
599 views
How to determine the sample distribution based on a survey involving six variables?
This question might be too naive, but I need to understand this point. Suppose I ran a survey for a product for 1000 individuals & collected the data for various aspects of it. Let's say the ...
15
votes
3answers
358 views
How to sample from $c^a d^{a-1} / \Gamma(a)$?
I want to sample according to a density
$$
f(a) \propto \frac{c^a d^{a-1}}{\Gamma(a)} 1_{(1,\infty)}(a)
$$
where $c$ and $d$ are strictly positive.
(Motivation: This could be useful for Gibbs ...
5
votes
1answer
201 views
How do I determine how well a dataset approximates a distribution?
Quite simple, I have some probability distribution p(x), how can I measure whether one empirical density (set of delta masses) is a better approximation than another. I know that KL-divergence is a ...
0
votes
0answers
147 views
Sampling distribution [editted] [closed]
With a given mean , standart deviation, How can one determine the mean and the sampling distribution of the sample mean for a*random* sample of size n ( n is known and, of course it is an national ...
4
votes
1answer
116 views
Who first developed the idea of “sampling distributions”?
Who created sampling distributions? I have looked everywhere and I'm writing a paper, but, so far, all I've been able to come up with is the theory and the definition. Please help me find the who, ...
4
votes
1answer
821 views
How to use/interpret empirical distribution?
First of all I'd like to apologize for the vague title, I couldn't really formulate a better one just now, please feel free to change, or advice me to change, the title to make it better fit the core ...
3
votes
2answers
132 views
Checking the distribution of classes in a sample of a dataset
I am new here, so I might have missed a similar question.
I am trying to do things good in my research and using proper statistical approaches, but in computer science, we had quite a weak training ...
8
votes
2answers
528 views
How to calculate sample size for simulation in order to assert some level of goodness in my results?
I am a stats newbie, so apologies in advance if I'm asking a braindead question. I have searched for answers to my question, but I find that many of the topics are either too specific, or quickly go ...
3
votes
1answer
284 views
Sampling with unequal bins?
I have a very simple model. This model uses data that are not given as continuous distributions, but are described by percentiles. What is the best way to sample these percentile bins, when the bins ...
