README file

The scripts in this repository can be used to reproduce the results in Mid-quantile mixed graphical models with an application to mass public shootings in the United States by L. Merlo, M. Geraci and L. Petrella.

Prerequisites

Software requirements

• R version 4.4.1 or higher
• RStudio version 2024.09.0+375 or higher
• Qtools version 1.5.9 or higher

The code has been parallelized using the following packages:

• foreach
• parallel
• doParallel

Dataset

The post-processed dataset is included in the excel file Mass_Shootings.xlsx in the data folder. The raw data (version 7 - Updated June 2023) can be freely downloaded at www.theviolenceproject.org/mass-shooter-database.The codebook can be found in the main body of the text and more detailed information can be found at www.theviolenceproject.org.

Script description

WorkHorse.R

This script contains the functions to run the R scripts in this repository. The main functions are:

• QMGM allows to fit the proposed mid-quantile mixed graphical model (QMGM).
• fit.cat allows to estimate the regression parameters of a LASSO-penalized mid-quantile regression.
• midCDF_est allows to estimate the conditional mid-CDF.

Data_preparation_Mass_Shootings.R

Preliminary step to clean the data and provide a suitable format for the analysis. This script can be used to reproduce Table 1 and Figure 2 of the paper.

• Table 1: Summary statistics of the variables in the sample.
• Figure 2: Number of fatalities per year and number of shootings per year.

Mass_Shootings_ave.R

This script can be used to reproduce Figures 3 and 4 of the paper.

• Figure 3: Estimated network structures from QMGM7 and MGM.
• Figure 4: Local centrality measures for the MGM and QMGM7 estimated networks.

Running the Script

1. Open the Mass_Shootings_ave.R script in RStudio.
2. At line 75-77, select the grid of quantiles tau.
3. Run the script.