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Questions tagged [subset]

1 set, A, is a subset of another, B, iff all elements of A are elements of B.

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27 views

Determining whether it matters which subset I pick from my dataset

I'm going to simplify my own research problem with the following example: Lets suppose I have N=40 students in my classroom. I need to select 20 of them to participate in a national math competition. ...
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1answer
9 views

Resample dataframe by random subset of years

I have a dataset of 59 years worth of daily rainfall data. I'd like to resample the data by 6 randomly selected years 1,000 times, using the entire year of data for each of the 6 years (so 2190 ...
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11 views

Sample subsets with distribution proportional to elementwise product

I have a set of $n$ elements, $x_1,x_2,\dots,x_n$, each with a weight $w_1, w_2,\dots, w_n$. I want to sample a subset of fixed size $k$ such that the probability of drawing $\{x_a,\dots,x_b\}$ is ...
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1answer
31 views

Unsupervised clustering of sequence of events to subsequences

I have a big dataset of M sequences of [1 - N] events, where each event has multiple properties (start date, end date, location, ...
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1answer
33 views

Why is the relationship between max(X,Y) and X and Y the way it is?

My textbook says that the above follows from the observation: $\{W\leq w\}=\{X\leq w\},\{Y\leq w\}$, How do we prove the above observation?
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1answer
27 views

Survival analysis with incomplete data

I would like to estimate the association between exposure to an environmental contaminant and all-cause mortality. Unfortunately the dataset I can get access to is incomplete - exposure data are only ...
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0answers
15 views

A non random subset of a distribution is similar to the original distribution, why?

I have near 1 million correlations between two groups of variables. The distribution looks normal for the distributions of interest (centered around 0 and symmetric): Using some other methods (not ...
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0answers
15 views

k-means and (re?) standardisation of a sub-set

I have data which is customer purchases of items in each of three months: I have summed the data over the three months for each customer; calculated the proportion of purchases that each item ...
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1answer
21 views

Dividing datasets into fully-correlating subsets

I have a dataset of $N$ variables of which I know that (at least) one combination of their disjoint subsets results in non-negative correlation coefficients for all variables in these subsets. The ...
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0answers
19 views

Consistency metric explanation

I am trying to understand a bit more about the consistency metric (to understand how consistency-based subset evaluation works). I find on this paper the following equation : $$\text{Consistency}_s =...
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0answers
23 views

When should a regression be run across the subsets of a population vs the entire population

At work we are looking to run some models on subsets of a population. For the sake of this post, I'll call the models created on subsets 'conditional' and the model run on the entire population '...
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44 views

Finding p-value of similarity between 2 networks

So, I want to calculate p-value of a case if possible. Suppose I have: set A with 1,295 elements set B with 493 elements number of same element between set A and B (intersection) is 478 From each ...
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1answer
50 views

Are the assumptions of subset selection violated of all the data comes from a single person?

I’m interested in using machine learning techniques such as subset selection, lasso and ridge regression to predict which words an individual kid will get wrong. I have about 300 predictors and all my ...
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47 views

Probability that 3 out of 4 sets have non-empty intersection

I have $4$ randomly sampled subsets from population set $S = \{1,2,...,100\}$. Each subset has size $24$. What is the probability that at least one element is common among $3$ out of $4$ subsets?
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0answers
67 views

Dealing with many NA's in very large datasets for Lasso

I have a few very large and quite "dirty" (survey) datasets. Primarily, there are lots of NA's. These NA's are mostly the result of different questions being asked in different waves. It is perfectly ...
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1answer
32 views

finding expected value when a set is given and a subset of size n is chosen

I found an interesting coding challenge on pramp by a friend but I couldn't do it in time. Anyhow, it says given a set { 3,14,7,22,29,33} and random 3 element subset is generated each time and its ...
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0answers
116 views

Vapnik-Chervonenkis Dimension

My question has to do with the VC dimension of the class of convex polygons with $m$ vertices. A solution to this problem is given in the following: Advanced Algorithms. Call the class of all ...
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1answer
44 views

Why low error indicates better model when only one feature is used?

In this lecture, starting from first minute, there is an example of features for housing application. Let's say number of features is 1. I understand why lowest error indicates better model, but why ...
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25 views

how to create a subset of models? [closed]

I want to select a specific models from a list of models generated by: m2 <- glm.nb(NroAnimales ~ anio + diaJuliano + I(diaJuliano^2) + BFmediana , data =datos, na.act ModelSel<-dredge(m2,rank=...
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1answer
88 views

How to create a subset that respect the same distribution of the original data set?

I have a presumably easy question for you, but I am a real newbie in statistics, so please be patient. I have a data set containing $N$ values that more or less follows a normal distribution. I need ...
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3answers
78 views

Is this an example of a multiple comparisons problem?

I am conducting a comprehensive research determining the effect of 3 independent variables on the metabolic rate of an organism. However, the set-up of my data analysis leads me to believe that I ...
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0answers
75 views

How many subsets have n values greater/lesser than values in remaining subset?

For example, given set of ten numbers: {0, 1, 2, 3, 4, 5, 6, 7, 8, 9} Split into two equal-sized subsets. Multichoose calculates 252 configurations of subsets with 5 values (pick 5 from 10). Only ...
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0answers
105 views

Similarity metric for sets of sets of nominal data

I felt it important to include the full motivation for my question, since part of my trouble I think is simply not knowing the terms to search for. Similarity of set of sets and Similarity metric ...
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1answer
63 views

ML method to identify data subset with lower average values?

I have a task where I need to find anomalous groups of observations [y,X] by the average value of y, using the feature set X. A good interpretation is that these are customers and I want to find the ...
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0answers
16 views

Subset with largest information gain

I am competing in a programming contest where the submission phase can be stated abstractly as follows : There is a known universe set, $U$, and a hidden target $T \subset U$. I submit $S \subset U$, ...
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4answers
333 views

Variance of set of subsets

First of all sorry for the sloppy terminology, but I am right looking for the name of a statistical concept. I was asked to calculate the "turnover" of the Facebook friends commenting on my posts, ...
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1answer
106 views

Decompose Covariance by Observations

Suppose I observe $n$ iid realizations of two random variables $X$ and $Y$, denoted respectively $x_i$ and $y_i$. Observations can be groupped into two subsamples, with $n_1$ and $n_2$ observations. I ...
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99 views

How to test whether subgroup is influential in overall group mean? (whether removing a subgroup affects results/all-but-subgroup mean != overall mean)

This question is similar to this one but I want to test whether the all-but-subgroup mean differs from overall group including the subgroup. This is DIFFERENT FROM THAT QUESTION in that the question ...
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0answers
207 views

How can I perform a two-sample multivariate t-test where one group is a subset of the other?

Is it possible to compare two means (ideally multivariate) where one comes from a group that is the subset of the other group? E.g. the first group consists of A, B, C, D, E subjects and the second ...
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0answers
45 views

Heteroscedasticity in Data, none in Subset

This might seem like a trvial questions to some but sadly not me. My dataset has heteroscedasticity and therefore I use a heteroscedasticity consistent standard error estimator (I use the RLM macro ...
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1answer
97 views

Small values are sorted incorrectly, subset() gives wrong data in R [closed]

I have a (gwas-)data where one column is p-value. P-values vary from $1*10^{-8}$ to $1$. I would want to have a subset where I have only values where p-value is $5*10^{-5}$ or lower. I have the ...
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1answer
26 views

Comparing N-way joint frequency distributions of different subsets?

Say I have binary variables: tall basketball player football player vegan programmer student We are also given subsets of a population. My objective is that I want find out what combination of ...
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0answers
14 views

Store outputs of Lm performed on conditional dataframe subsets?

I am trying to store the regression's slopes of two variables recorded for different individuals through a season. What I would like is the slope of the regression for each individual for each day (...
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0answers
50 views

Bias in forward stepwise selection in regression

Let $Y=X\beta+E$ be a linear model with p variables and suppose that we perform som subset selection and we only use k variables where $k<p$. I want to get the biase os the new model. I call $X=(...
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0answers
123 views

Find a subset of input data space with high classification accuracy?

I'm having what would seem to be quite a general and widely applicable problem but I can't find literature on the subject. Example problem: Imagine I have medical records of thousands of patients (...
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0answers
9 views

How to properly select elements to tag manually for building training and test sets?

I have to select a subset (short texts like comments and twitter posts) out of a huge population to tag them manually for building a sentiment analysis training and test set. How should I select these ...
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0answers
441 views

ISLR book ridge/lasso regression cross-validation

I work with the book 'Introduction to statistical learning with R', link. I got a question about the cross-validation for ridge and lasso regressions (ellipsis indicate that part of the original code ...
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1answer
479 views

Subset Sum with Constraints

I'm taking a look at what I have identified as being a subset sum problem. I have around 650 potential values which could form part of my single sum value. I've began looking into the typical ...
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1answer
294 views

Using blocking in propensity score analysis?

I'm considering blocking my analysis dataset on one or two key variables prior to a standard sub-classification propensity score analysis. For example, if my dataset (which contains member level pre- ...
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2answers
177 views

Bias in average age for grandmaster title qualification by age groups?

It has been known for quite some time that the youngest age at which chess players managed to qualify for the grandmaster title has significantly decreased since the 1950s, and there are currently ...
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0answers
231 views

R: subsetting survey design fails after raking

all. I hope you can help me with a problem I encountered while analyzing data from a survey. I have actually done all the analysis, but after that obtained more reliable data about the population ...
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1answer
48 views

Unable to figure out equation with set probabilities

I am currently self-studying with Casella & Berger and there is a problem that has me stumped. Please note I am NOT asking for a solution, I just need clarification on the terms used. Here is the ...
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0answers
41 views

Significance for the whole dataset of detections in a subsample

I have a fairly simple question, but I am not so familiar with these problems so I would like to ask. If I have, let's say, 4 data samples belonging to the same overall population. If in a test a ...
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1answer
524 views

Predicting from RPart using a subset of variables

I fitted a RPart model from all of a couple dozen variables. Now, I want to test predictions using just a couple of variables that seem significant to me. If it was the iris dataset, for example, I ...
2
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1answer
214 views

Membership probability for distributions over subsets

Fix a set $\mathfrak{A}$ and a probability distribution $\mathcal{D} : 2^\mathfrak{A} \to [0,1]$ defined over subsets of $\mathfrak{A}$. We can then ask "what is the probability $p(x)$ that a subset ...
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2answers
130 views

Is it needed to train the selected model again on entire data before putting in production?

When a dataset is needed to be modeled, the process is to take a part of it out as holdout set which is "unseen" by the training method and is used to test the performance of models created using ...
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1answer
57 views

Testing variables in meta-analysis

I am conducting a meta-analysis of cognitive-behavioural interventions on self-esteem and I could use some assistance navigating through the statistical procedures. I have extracted pre-post scores ...
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1answer
680 views

How does one go about determining the standard deviation of an entire sample data set?

I have frequently been faced with analyzing csv files that are limited in length to approximately 32,000 records in length (overflows at 32,768, from signed integer limits on a 16 bit wide data bus). ...
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1answer
29 views

Subselect Package R - The covariance/total matrix supplied is not symmetric?

I was trying out the Subselect R package to see how it worked and if it would be useful for a logistic regression problem I'm working on. Link to the package. I decided I would follow Example 4 on ...
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1answer
3k views

Can forward and backward selection give the same model?

I'm using forward stepwise selection and backward stepwise selection to produce models in R. However, I got the exactly same model for two different methods. Is that normal? ...