Estimates the number of communities (dimensions) of a dataset or correlation matrix using a network estimation method (Golino & Epskamp, 2017; Golino et al., 2020). After, a community detection algorithm is applied (Christensen et al., 2023) for multidimensional data. A unidimensional check is also applied based on findings from Golino et al. (2020) and Christensen (2023)

## Arguments

- data
Matrix or data frame. Should consist only of variables to be used in the analysis. Can be raw data or a correlation matrix

- n
Numeric (length = 1). Sample size if

`data`

provided is a correlation matrix- corr
Character (length = 1). Method to compute correlations. Defaults to

`"auto"`

. Available options:`"auto"`

— Automatically computes appropriate correlations for the data using Pearson's for continuous, polychoric for ordinal, tetrachoric for binary, and polyserial/biserial for ordinal/binary with continuous. To change the number of categories that are considered ordinal, use`ordinal.categories`

(see`polychoric.matrix`

for more details)`"cor_auto"`

— Uses`cor_auto`

to compute correlations. Arguments can be passed along to the function`"pearson"`

— Pearson's correlation is computed for all variables regardless of categories`"spearman"`

— Spearman's rank-order correlation is computed for all variables regardless of categories

For other similarity measures, compute them first and input them into

`data`

with the sample size (`n`

)- na.data
Character (length = 1). How should missing data be handled? Defaults to

`"pairwise"`

. Available options:`"pairwise"`

— Computes correlation for all available cases between two variables`"listwise"`

— Computes correlation for all complete cases in the dataset

- model
Character (length = 1). Defaults to

`"glasso"`

. Available options:`"BGGM"`

— Computes the Bayesian Gaussian Graphical Model. Set argument`ordinal.categories`

to determine levels allowed for a variable to be considered ordinal. See`?BGGM::estimate`

for more details`"glasso"`

— Computes the GLASSO with EBIC model selection. See`EBICglasso.qgraph`

for more details`"TMFG"`

— Computes the TMFG method. See`TMFG`

for more details

- algorithm
Character or

`igraph`

`cluster_*`

function (length = 1). Defaults to`"walktrap"`

. Three options are listed below but all are available (see`community.detection`

for other options):`"leiden"`

— See`cluster_leiden`

for more details`"louvain"`

— By default,`"louvain"`

will implement the Louvain algorithm using the consensus clustering method (see`community.consensus`

for more information). This function will implement`consensus.method = "most_common"`

and`consensus.iter = 1000`

unless specified otherwise`"walktrap"`

— See`cluster_walktrap`

for more details

- uni.method
Character (length = 1). What unidimensionality method should be used? Defaults to

`"louvain"`

. Available options:`"expand"`

— Expands the correlation matrix with four variables correlated 0.50. If number of dimension returns 2 or less in check, then the data are unidimensional; otherwise, regular EGA with no matrix expansion is used. This method was used in the Golino et al.'s (2020)*Psychological Methods*simulation`"LE"`

— Applies the Leading Eigenvector algorithm (`cluster_leading_eigen`

) on the empirical correlation matrix. If the number of dimensions is 1, then the Leading Eigenvector solution is used; otherwise, regular EGA is used. This method was used in the Christensen et al.'s (2023)*Behavior Research Methods*simulation`"louvain"`

— Applies the Louvain algorithm (`cluster_louvain`

) on the empirical correlation matrix. If the number of dimensions is 1, then the Louvain solution is used; otherwise, regular EGA is used. This method was validated Christensen's (2022)*PsyArXiv*simulation. Consensus clustering can be used by specifying either`"consensus.method"`

or`"consensus.iter"`

- plot.EGA
Boolean (length = 1). Defaults to

`TRUE`

. Whether the plot should be returned with the results. Set to`FALSE`

for no plot- verbose
Boolean (length = 1). Whether messages and (insignificant) warnings should be output. Defaults to

`FALSE`

(silent calls). Set to`TRUE`

to see all messages and warnings for every function call- ...
Additional arguments to be passed on to

`auto.correlate`

,`network.estimation`

,`community.detection`

,`community.consensus`

, and`community.unidimensional`

## Value

Returns a list containing:

- network
A matrix containing a network estimated using

`link[EGAnet]{network.estimation}`

- wc
A vector representing the community (dimension) membership of each node in the network.

`NA`

values mean that the node was disconnected from the network- n.dim
A scalar of how many total dimensions were identified in the network

- correlation
The zero-order correlation matrix

- n
Number of cases in

`data`

- dim.variables
An ordered matrix of item allocation

- TEFI
`link[EGAnet]{tefi}`

for the estimated structure- plot.EGA
Plot output if

`plot.EGA = TRUE`

## References

**Original simulation and implementation of EGA**

Golino, H. F., & Epskamp, S. (2017).
Exploratory graph analysis: A new approach for estimating the number of dimensions in psychological research.
*PLoS ONE*, *12*, e0174035.

**Current implementation of EGA, introduced unidimensional checks, continuous and dichotomous data**

Golino, H., Shi, D., Christensen, A. P., Garrido, L. E., Nieto, M. D., Sadana, R., & Thiyagarajan, J. A. (2020).
Investigating the performance of Exploratory Graph Analysis and traditional techniques to identify the number of latent factors: A simulation and tutorial.
*Psychological Methods*, *25*, 292-320.

**Compared all igraph community detection algorithms, introduced Louvain algorithm, simulation with continuous and polytomous data**

**Also implements the Leading Eigenvalue unidimensional method**

Christensen, A. P., Garrido, L. E., Pena, K. G., & Golino, H. (2023). Comparing community detection algorithms in psychological data: A Monte Carlo simulation.

*Behavior Research Methods*.

**Comprehensive unidimensionality simulation**

Christensen, A. P. (2023).
Unidimensional community detection: A Monte Carlo simulation, grid search, and comparison.
*PsyArXiv*.

**Compared all** `igraph`

**community detection algorithms, simulation with continuous and polytomous data**

Christensen, A. P., Garrido, L. E., Guerra-Pena, K., & Golino, H. (2023).
Comparing community detection algorithms in psychometric networks: A Monte Carlo simulation.
*Behavior Research Methods*.

## See also

`plot.EGAnet`

for plot usage in `EGAnet`

## Author

Hudson Golino <hfg9s at virginia.edu>, Alexander P. Christensen <alexpaulchristensen at gmail.com>, Maria Dolores Nieto <acinodam at gmail.com> and Luis E. Garrido <garrido.luiseduardo at gmail.com>

## Examples

```
# Obtain data
wmt <- wmt2[,7:24]
# Estimate EGA
ega.wmt <- EGA(
data = wmt,
plot.EGA = FALSE # No plot for CRAN checks
)
# Print results
print(ega.wmt)
#> Model: GLASSO (EBIC with gamma = 0.5)
#> Correlations: auto
#> Lambda: 0.0648639582532287 (n = 100, ratio = 0.1)
#>
#> Number of nodes: 18
#> Number of edges: 96
#> Edge density: 0.627
#>
#> Non-zero edge weights:
#> M SD Min Max
#> 0.082 0.060 -0.013 0.363
#>
#> ----
#>
#> Algorithm: Walktrap
#>
#> Number of communities: 2
#>
#> wmt1 wmt2 wmt3 wmt4 wmt5 wmt6 wmt7 wmt8 wmt9 wmt10 wmt11 wmt12 wmt13
#> 1 1 1 1 1 2 2 2 2 2 2 2 2
#> wmt14 wmt15 wmt16 wmt17 wmt18
#> 2 2 2 2 2
#>
#> ----
#>
#> Unidimensional Method: Louvain
#> Unidimensional: No
#>
#> ----
#>
#> TEFI: -11.171
# Estimate EGAtmfg
ega.wmt.tmfg <- EGA(
data = wmt, model = "TMFG",
plot.EGA = FALSE # No plot for CRAN checks
)
# Estimate EGA with Louvain algorithm
ega.wmt.louvain <- EGA(
data = wmt, algorithm = "louvain",
plot.EGA = FALSE # No plot for CRAN checks
)
# Estimate EGA with an {igraph} function (Fast-greedy)
ega.wmt.greedy <- EGA(
data = wmt,
algorithm = igraph::cluster_fast_greedy,
plot.EGA = FALSE # No plot for CRAN checks
)
```