Questions tagged [subset]

One set, A, is a subset of another, B, if and only if all elements of A are elements of B.

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16 views

Need help understanding paper by Jolliffe - various methods in choosing subsets for PCA

There's a paper I'm trying to base some work off of called Variable Selection and the Interpretation of Principal Subspaces which uses some various methods to choose subsets of variables. Their ...
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25 views

When is subsetting survey data prior to analysis NOT a problem?

Survey researchers are typically advised to not subset their data prior to analysis because it will produce incorrect variance estimates. My understanding of the inferential issue is that removing ...
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7 views

Uncertainty when taking the difference between a measurement and a subset measurement

Lets say I collected $\mathbf{N_t}$ data points for an experiment and this resulted in a measurement of $A\pm\sigma_A$. Then I'm interested in how a particular variable effects the study and remove $\...
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14 views

Maximizing a subset's variance

Consider the given set [x_1, ... , x_n]. For a fixed natural number M, I want a subset [x_(i1), ..., x_(iM)], whose cardinality ...
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14 views

Compare models from different data subsets [duplicate]

I'm looking to compare linear regression models from different data subsets in r. The models are not nested. I have a model from the complete dataset with sex as a factor and then 2 separate models ...
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67 views

Is it preferable to subset data to test specific hypotheses or specify a full model and run contrasts?

Let's say I have a 2x2 design where participants are either in condition A or condition B and, within each condition, either get exposed to exposure C or exposure D. First, I want to test whether ...
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1answer
31 views

Logistic regression balanced dataset

I am quite inexperienced using logistic regression and am having trouble understanding my data and how the regression behaves. Here's the outline of my problem: I have a (medical) test that gives a ...
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1answer
94 views

Is there a name for the increase in variance upon remeasurement after subsetting with a cut-off value?

Context: My problem relates to estimating effect sizes, such as Cohen's d, when looking at a subset of the population defined by a cut-off threshold. This effect size is the difference in two ...
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31 views

How to treat apples and oranges best in multiple regression analysis? One fits all regression model or separate sub models? [duplicate]

I have a data set ready for multiple regression analysis that consist of apples and oranges. Let's say the depended variable is fruit size and there is a bunch of independent variables (categorical &...
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2answers
25 views

Relationship between deterministc function of random variables

Given a discrete $P(X,Y,Z)$ let's call $\Omega$ the set of all deterministic functions $f: XYZ \rightarrow W$ and $\Omega'$ the set of all deterministic functions $f': XY \rightarrow V$. Is it correct ...
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12 views

How to test if the subset is representative to whole dataset

I would like to ask how to test if the subset is representative to the whole dataset. I have for example 150 values in whole "population" and I selected (not randomly) 30 of them. I would ...
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15 views

Reduced chi-squared for models fit to different subsets of data

I have some data to which I am fitting piecewise linear models. I want to select different subsets of the data, fit a model to each of them, and then compare which subsets are best able to be ...
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9 views

Subset dataframe by conditioning on two observations within a column for each subject (group)

I am looking to compare the results of a survey (not shown) before and after teaching. You can see below that the last column column specifies whether this observation contains the information from &...
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11 views

Check if a subset is significantly different from the dataset

I have a dataset with violence rate per City that can be grouped by State. I need to check if any State has significantly different violence rates than the entire dataset. How could I achieve that? ...
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1answer
18 views

How to isolate a linearly correlating subset from data?

I have a data set of a few thousand data points, and some of them show strong linear correlation. I would like to isolate these data points into their own subsets. What would be the best approach for ...
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73 views

GLM in R: Subset Covariate to specific factor Levels

I like to conduct a GLM in R like this: glm ( Y ~ X + Z + a + b + c + d, quasipoisson(link="log")) with Y as dependent Variable (Count Data, integer) X as ...
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26 views

Difference between stratification and subset

This may be a duplicate question asked differently, I am curious to know the difference between performing an analysis by stratification on a variable and by subsetting the dataset based on that ...
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389 views

Probability problem - Probability to pick a subset divisible by 3

I'm trying to solve this puzzle but I get stuck. I thought about trying to use the law of total probability to solve intermediate problems with subset of size k but it didn't helped me that much. Is ...
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1answer
24 views

Unsupervised Subspace learning for different Tasks

once we extract subspaces(subset of features) for a dataset using unsupervised learning, can we use them for any task I mean for classification, clustering, or outlier detection? Is the selection of ...
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67 views

What is it called when we “zoom in” a data distribution?

Suppose we have a 2D distribution of shops in an area. For example, here is a heatmap density plot of (latitude, longitude) location of shops in a province: Now suppose that we "zoom into" the ...
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65 views

Is it appropriate to include overlapping sub-scale scores and total-scale scores in a meta-analysis?

Question, brief In a single multi-level meta-analysis, is it appropriate to include subscale scores (which represent part of a measure) in addition to total scale scores (representing the full ...
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102 views

Q: AUC of each subgroup is smaller than overall AUC

I have a validation data set of 29242 patients, with known labels/health outcomes and predictions that were generated by some model. 28626 patients are negative and 616 are positive The overall AUC is ...
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1answer
68 views

How to test that a subset of data is distributed no differently than original (discrete, not normal)

In the research I am doing we have initially had ~600 samples which had a certain distribution (not normal, although close). The characteristic of these samples that I am interested in is discrete (...
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1answer
35 views

Compact encoding (vectorization) of unbounded sets

Question I have a set of sets. Each set is unbounded. I would like to find a methodology to encode (vectorize) each subset. I am more specifically interested in memory efficient solutions. ...
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2answers
599 views

Determine how similar groups of data are to each other

I have a pool of 15,000 unique* items. From that set, there are roughly 3200 sets of 60 items, selected non-randomly (in fact, for the sake of the framing of the question, let's say that each item is ...
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1answer
11 views

Inferential considerations when comparing a group against the total

I want to compare the value of a subgroup against the same value in the total population in a regression setting. The easiest way to do it would be to treat the subgroup and the total dataset as two ...
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1k views

How to calculate number of sets in Sigma Algebra

The example 1.2.2 of the book Statistical Inference by Casella and Berger states: if S has n elements, there are 2^n sets...(please see attached). Could you please explain how the authors derived ...
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45 views

relation between conditional probability of subset and set

Suppose $A\subseteq B $. Can we derive a relationship between P(X|A) and P(X|B) for some X? X is associated with A.
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72 views

Why do subset selection linear models have higher variance than the full model?

I do not get the meaning of this sentences from the Elements of Statistical Learning book when talking about subset selection methods before introducing shrinkage methods. By retaining a subset of ...
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24 views

L sets and Probability theory

I am required to prove the following: Let $L_1$ be the space of real-valued random variables on $(\Omega,\mathscr{A},\mathbb{P})$ which have finite expectation $\mathbb{E}(|X|)<\infty$ and let $...
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64 views

Problem with significance of results from regression on subset of data

I have performed a hedonic regression with a database where all the variables are very significant and according to the calculations made in R with a squared R = 0.6123. I have performed the same ...
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27 views

Represent roles intersections

I have 11 roles, who defines rights (read, edit, write) on my application. For exemple I have "Inventory" who contains ressources_read and ...
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1answer
285 views

What statistical distribution test to use for comparing Dataset and its subset? [duplicate]

I have two sets, A and B ,containing height of students. Set A contains height of all students in the class and Set B contains height of some students from the same class. Hence, Set B is a subset of ...
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28 views

Which is the event, sample and population, notation confusion

I am really struggling with the notation for this. Below is the slide material followed by what I think it means/where I get stuck. "Some unknown real world quantity $\Theta$ takes values in $\Omega$....
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36 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
16 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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42 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
247 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
42 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
34 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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17 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
34 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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103 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
88 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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58 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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109 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 ...
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1answer
467 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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146 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
46 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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1answer
569 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 ...