1
vote
0answers
90 views

Sub sampling a dataset without losing the distribution

Suppose that I have a huge data set with high number of dimensions (components). For computational purposes I would like to take just a sample of this data set and work with it instead of working with ...
1
vote
0answers
66 views

Gibbs sampling in document clustering

I'm trying to understand the idea behind the Topic Models in document clustering. In Latent Dirichlet Allocation, it is necessary to approximate the posterior distribution of topics over the document. ...
4
votes
2answers
863 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 ...
2
votes
0answers
32 views

seeking statistical measures to use when evaluating a facial photo's “quality”

I have a large set of facial photos and a facial feature finder which helps me locate faces with a general idea of the location of the eyes, nose, mouth, and a curve outlining the face. These facial ...
1
vote
1answer
132 views

What should I do while designing stratified cluster randomized sampling survey if cluster size is large/smaller than I expect?

I am design a sampling strategy for a health survey in long-term care facilities (LTCFs). I refer to the article here and want to ask question about the cluster size. I am thinking of doing a ...
4
votes
3answers
269 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 ...
4
votes
0answers
227 views

How do I adjust standard errors in a research study in which the control group is constructed via matching with replacement?

I have a treatment sample of 200 firms. I'm using propensity score matching to pair each treatment observation with one control (sampling with replacement, in order to minimize bias associated with ...
1
vote
2answers
305 views

How to sample clustering to estimate precision and recall?

There is a system containing $N$ clusters and in each cluster there are some elements. The clusters' sizes varies dramatically and most of the clusters are singletons. I need to know the precision ...
1
vote
1answer
96 views

Finding k-representatives from a 2 dimensional data set

I have a data set for second hand vehicle sales with 2 variables price and kms covered. If we plot these data in a 2-dimensional plane, the points will form scattered chart. I would like to select k ...