Questions tagged [networks]

Refers to network theory as part of the graph theory. For questions about neural networks, use our [neural-networks] tag.

82 questions with no upvoted or accepted answers
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6
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0answers
134 views

Test whether cross-sectional dependence in panel data follows known (network/spatial) structure

I want to test whether cross-sectional dependence in one specific variable (y) in panel data format follows a known structure (W) (e.g. network, spatial dependence), after controlling for individual ...
5
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0answers
149 views

Time series for network matrices?

Let's say I have two people. Each of whom I create a network matrix for daily for some of their daily habits $(i.e. A, B, C, D)$. I do this for, let's say $60$ days. Two People and their daily ...
4
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1answer
65 views

Statistical test to identify enriched edges in a network

I have a network with N nodes and E directed edges. Each edge (Eij) is an integer that represents the number of connections between a source node (Ni) and a target node (Nj). My null model is that ...
4
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0answers
91 views

Machine Learning and Flow Maximization

Has anyone ever seen machine learning (ML) used to assist a Max Flow algorithm? I have a very large directed graph that has some fractal characteristics, meaning that this large graph can be roughly ...
4
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0answers
145 views

How to perform exploratory factor analysis on associative network?

In an article by Teichert and Schontag ("Exploring Consumer Knowledge Structure Using Associative Network Analysis", 2010), the authors perform (page 387) an exploratory factor analysis (EFA) on an ...
3
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0answers
47 views

How to measure “cyclicity” of a directed weighted graph?

Say you have a weighted directed graph with (potentially) some cycles in it. You want to have some sort of a measure of how "cyclical" this graph is. The requirements are: This measure C=0 on an ...
3
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0answers
114 views

Modeling products (from sales data) in a graph network for clustering and product recommendations.

I have a high level question about whether or not graph networks would be an appropriate method to model a situation I'm studying. It's been a while since I last worked on a project building/analyzing ...
3
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0answers
200 views

Nodes placement in knowledge map of Khan Academy

I have been through the Khan Academy blog regarding construction of knowledge map. However after going through it, it left me confused regarding how are they placing the nodes (hierarchically) and ...
3
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0answers
758 views

Pagerank vs Eigenvector centrality

What are the practical differences between PageRank and Eigenvector centralities? I don't mean the differents in how to compute the centralities, but the information they provide of a set of nodes in ...
3
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1answer
397 views

Comparing adjacency matrices

I have 25 weighted adjacency matrices which can be potentially translate into 25 networks. I want to see how ``similar'' are the resulting networks (in a graph theory sense). Is there a way to do ...
3
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0answers
94 views

Missing values with Community structure in networks?

Is there a way to predict Missing values with Community structure in networks? I have a data set with a couple dozen variables, such as age, level of education, self-assessed (via a Likert scale) ...
3
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0answers
974 views

Plot directed acyclic graph with scaled edge length

I am trying to design a network (more precisely a directed acyclic graph) with specific edge lengths. The data is on the form of an edge list, and for each edge, there is an associated length. It ...
3
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0answers
56 views

Relations and differences between graphical models and stochastic networks?

Do both graphical models and stochastic networks (e.g. http://people.cs.pitt.edu/~milos/networks/) mean the same concept: there is an underlying graph, each vertex corresponding to a random variable, ...
3
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0answers
167 views

What is a statistical test of whether a variable is uniformly distributed with kinks?

I am trying to come up with a way to statistically test this question, and could use some input, as it's far afield from what I normally do. I have a hierarchical network, like this one: And a ...
3
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0answers
153 views

Kavosh uses a different switching process in its MCMC; how concerned should I be?

Kavosh is a recent package designed for network motif discovery. To give a comparison, Kavosh generates a collection of similar networks using an MCMC process. The networks in consideration are ...
2
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0answers
132 views

Network modularity for exactly two communities

I have a number of empirical networks that tend to show bipolarization patterns, meaning that there are precisely two communities. In some networks, the two communities are very clearly separated (...
2
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0answers
201 views

Random Forest for financial networks modelling

One of the hottest topics in today econometrics is financial networks models where researches use vector autoregressive (VAR) models applied to time series of daily volatility measurements of ...
2
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1answer
48 views

To test for small-world property, does the random graph generated has to be completely connected?

For a small world property, the ratio of the average path length and the mean path length of random networks has to be close to one. My question is: When generating a random graph using the Erdős-...
2
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0answers
395 views

Network science: How to calculate assortativity (Pearson's correlation) coefficient for this small network?

Let $A$ denote a weighted, directed network, where the weights in the rows are the out-degrees, and weights in the columns are the in-degrees: $A$ = \begin{bmatrix} 0 & 0 & 0 \\ 1 &...
2
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0answers
800 views

How to deal with Network Effects in AB Testing?

Say you wanted to AB test a particular treatment on a social network and measure the number of shares. Unfortunately, this is a very naive metric to use because we aren't accounting for the network ...
2
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0answers
350 views

Comparing factor structure to network analysis using a community detection algorithm

I am interested in the use of weighted correlational network analysis to explore high dimensional data, instead of latent variable models like exploratory factor analysis (EFA). My approach is to: ...
2
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0answers
64 views

More than one function of a single instrumented endogenous variable — is the model still underidentified?

The typical instrumental variable setup seeks a consistent estimate of $\beta$ from $$ y = \alpha + \beta x + \epsilon $$ where $cor(x,\epsilon) \neq 0$, in the univariate case, without loss of ...
2
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0answers
117 views

Predictive model for network data

Assume a network as a set of data, which are defined by their coordination $(x,y,z)$ and a weight on its edge. Now this data can be used as an input data to predict a single value. In my case, ...
2
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0answers
520 views

Queueing Theory: How to estimate steady-state queue length for single queue, N servers?

I have a real-life situation that can be solved using Queueing Theory. This should be easy for someone in the field. Any pointers would be appreciated. Scenario: There is a single Queue and N ...
1
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0answers
19 views

Regression with autocorrelation given by a graph

Supppose I would like to fit a standard regression model of the form $y = \alpha + X \beta + \epsilon$, but my observations come from a networked population (eg. social network). I have the graph $G$ ...
1
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0answers
26 views

Reference request: Network/graph topology inference

I am a mathematician looking for a survey/book on methods for inference of graph/network topology (structure). Specifically, the kind of problem I am looking to study is as follows: Given a graph $...
1
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2answers
45 views

Missing values in a variable depending on the values of another variable

I'm working on a public procurement dataset where I have information on all the participants that presented offers in 358 tenders. I'm analysing relationships between all the companies of the dataset (...
1
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0answers
63 views

Quantifying information loss between a graph and a hypergraph

In some of the literature relating to hypergraph applications, there is an argument about information loss when representing data as a graph compared to a hypergraph. For example, the well known ...
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0answers
209 views

How to implement weighted centrality in NetworkX

I am using the following code to try implement eigen-vector centrality for a weighted graph G. The nodes represent search terms and the is an edge from node A to node B if someone searches for A and ...
1
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0answers
162 views

Interpretation of Modularity in R

I used modularity maximization cluster method to make 3 different clusters (4, 5 and 6 clusters) from a network using "Igraph" in R. I found the modularity of the three networks are 0.15, 0.23, and 0....
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0answers
63 views

Transforming dissimilarity matrix for use as weights in network

I'm trying to identify communities or clusters in a network by optimizing the modularity function. The network is a fully connected network, with undirected edges that have weights based on a pairwise ...
1
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0answers
44 views

Graph Theory / Network Analysis - properties variation

I have a rather complex network (air travel in the US) with more than 500 nodes, and small-world, scale-free proprieties, spanning over 10 years, and with quarterly information. As I'm trying to ...
1
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0answers
48 views

Request for references: Best way to estimate directed graphs *with* cycles

I have $n$ observations of $p$ random variables $\{Y_1,\dots,Y_p \}$. I know that each observation has been generated from a linear network model of the form $$ Y = WY+\epsilon $$ and that the graph ...
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0answers
72 views

Network analyses on probabilistic graphical models

I recently see examples of network analyses (such as centrality measures from network/graph theory) being applied on probabilistic graphical models (e.g. Gaussian graphical model) and there is a ...
1
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0answers
236 views

Setting initial assignments for mixed-membership stochastic blockmodel

I created two networks at two points (in the middle of the month and at the end of the month). Tried to run mmsb.collapsed.gibbs.sampler for the first network and obtained network communities. However,...
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0answers
466 views

Input to fit a power-law to degree distribution of a network

I would like to use R to test whether the degree distribution of a network behave like a power-law with scale-free property. Nonetheless, I've read diferent people ...
1
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0answers
12 views

Term for node measure of flow importance

I'm looking for a term describing measures that relate to the importance of nodes/vertices in a graph in controlling flow. Nodes that sits in between dense clusters would be scored highly while highly ...
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0answers
22 views

Finding correlation between size, weight and location in a network graph

I have an undirected graph of students, their friendship ratings, and amount of effort paid in class in the following format: ...
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0answers
237 views

How to decide if a relationship network(graph) is directed or undirected?

I have a dataset that consist of the following information: Person_1 (from node), Person_2 (to_node), Home_Room_Location (of person_1), Time_Spent_Together (treating this as weight). I've been ...
1
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0answers
68 views

Variational inference in the directed network in Airoldi's Mixed Membeship Stochastic Blockmodel

$\newcommand{\E}{\mathbb{E}}$I was dealing with derivations for the variational parameters in the model proposed by Airoldi, Blei, Fienberg, and Xing, 2008 for overlapping communities using a mixed-...
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0answers
140 views

Running an exponential random graph model (ERGM) with lagged covariates

at the moment I am trying to fit an exponential random graph model (ERGM) in R with the function 'ergm' that comes with the 'statnet' package. Here I have two questions. One is of technical nature and ...
1
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0answers
126 views

How to explain conditional independence between two nodes in a Bayesian network for some values of another node but not all?

Imagine three back to back directed nodes. A -> B -> C Knowing B, A and C are ought to become independant. Imagine B to be binary A & C have positive correlation. After I correct for B, for B=...
1
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1answer
54 views

Which graph/network format should be used when releasing a data set?

Under RENOIR (an EU funded project) I am working on releasing the data set of Slovenian Press Agency for researchers and other folk. As part of the data set we will be releasing some graphs with ...
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0answers
33 views

State-dependent tandem network of queues

I've been studying network of queues and I would like to model a system by a tandem state-dependent network of queues. I know Jackson network works for $M/M/$ networks, but not for queues where the ...
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0answers
17 views

Need to solve a “pseudo-metabolic” network for rates

Sorry about the re-post from Biology section... following problem: I have data on a certain complex association network (from monomers 1 ... 8 to complexes of all combinations, such as, 12 ... 13 ... ...
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0answers
52 views

how to quantify the dependence between two sparse signals?

Hi and thank you for your help. I am happy to provide more context/details. In my research, I have a system that has many sensors X_1..X_N and using this ...
1
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0answers
47 views

Relationship between P(A|X,Y), P(X|Y) and P(A|X)?

My statistics training is only basic, so forgive any embarrassing misunderstandings. Here's my situation: I have a graph (a big one) with 20,770 nodes. This is Y. I have a subgraph, X (subset of Y),...
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0answers
291 views

Borgatti Key Player Problem (KPP) in Python

Has anyone come across any Python implementation of Borgatti's proposed Key Player Problem (KPP) algorithms? I'm interested in solutions using NetworkX and particularly interested in implementations ...
1
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0answers
81 views

What is a proper scale to do the social network analysis?

Problem My problem is to profile the individual user (i.e. mine individual user's interest, location, and many more). What we have as input are the network structure (e.g. linked-in network) ...
1
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0answers
500 views

Network graph: hypothesis test that degree distribution is becoming more equitable

I'm playing around with network graphs and am wondering how to show that there is: a statistically significant difference in in-degree distribution between nodes for 2 time periods the in-degree ...