GraphVar

Error using Rich Club Coefficient, Generating Random Networks and GLM

Submitted by David de Wied on
Forums

Hey GraphVar team,

Thank you for all you hard work in making this tool. Sadly, I've been having a few issues. 

When attempting to look at Rich Club coefficient (also using freshly installed Sample Workspace data), I get the following error:

Difference between "rand NW" and "permutation" in GLM panel

Submitted by veraP_20 on
Forums

Dear GraphVar team,

I want to use a nonparametric test to do a group comparison, but I don't know which of the two options of non-parametric test would be apropriate. Could you explain me the difference between them? I think in my case it would be the "permutation" option , but I would like to be sure.

All the best,

Vera.

Error Using Normalization

Submitted by RaviBot on
Forums

Hello, 

I am importing thresholded weighted, undirected matricies (symmetric) into GraphVar from an outside progam. These networks/matricies are all not fragmented (checked using the CheckFrag button). I am randomizing using the random_und_connected function however when I try to calculate cetain graph metrics such as betweenness centralitity, I get an error saying "Normalization error: some metrics derived from random networks result in zero which can not be used for normalization." 

Could someone please advise on what could be the issue? Thanks in advance!

GraphVar_v_1.03 Bugfix binary Clustering Coefficient

Submitted by Johann Kruschwitz on
Forums

Dear GraphVar-users,

We found that in the GraphVar 1.0 update, the function to calculate the clustering coefficient
for binary undirected graphs was accidentally replaced with a function to calculate the number of
triangles around each node. The clustering coefficient, however, is defined as the number of triangles
around each node divided by the number of possible triangles. In other words, the values that were
returned are simply the unscaled form of the binary undirected clustering coefficient.

Extracting data

Submitted by hpsig86 on
Forums

Hi.

Is it possible to extract local metric data (e.g., local efficiency values) from a single group regression analysis post regressing out nuisance variables? I.e. in a similar way as to select only control group or only patient group in group analysis at the bottom of the results viewer (I ran two separate analyses). That way I could plot local efficiency values on a specific node against a clinical measure.

Many thanks,

Hilmar

Type of statistical test in GraphVar Turbo

Submitted by hpsig86 on
Forums

Dear GraphVar team.

I just wanted to ask what sort of statistical tests are used while doing the following comparisons using GraphVar GLM Turbo (for reference I am using structural connectivity matrices from DTI tractography as inputs):

1) Having "Group" (patients vs controls) as a between factor and three variables as nuisance covariates. I.e. assessing differences between the two groups on graph metrics. Are the nuisance covariates regressed out prior to t-tests?

NBS for two 'mean' graphs

Submitted by DKIV4 on
Forums

Good Afternoon,

I have a quick question regarding the use of the NBS statistics toolbox within Graphvar. If I have two groups and from each have calculated a mean network for each group, can I use the NBS package to compare the two mean graphs. I worry that this wouldnt be statistically valid in the sense that the sample would effectively be two. 

Instead would I need to run a test like the hamming distance to compare two individual mean networks? If so is this within the scope of the Graphvar program?

GrapVar v_1.02 bugfix continuous by continous interactions

Submitted by Johann Kruschwitz on
Forums

We just uploaded a new GraphVar version that entails an important bugfix for continuous by continous interactions.

Release info GraphVar 1.02:

1. Fixed a bug where the direction of the effect of continuous by continous 
   interactions was reversed in some models. This issue did not affect the
   p-values of the regressors.
 
Best,
Johann