This project contains materials and a preregistration relating to a Stage 1 Registered Report entitled "Why are beliefs in different conspiracy theories positively correlated across individuals? Testing monological-network vs. unidimensional factor model explanations". Most of the files provided were created by the project team, with following exceptions: - The file "Swami et al 2017 data.csv" is data from Swami et al. (2017, https://doi.org/10.1371/journal.pone.0172617). This data was obtained via https://figshare.com/s/56cfd775e117dfc53552 (.sav, then converted to .csv using SPSS). This data was shared by Swami et al. using a CC-BY-4.0 licence (https://creativecommons.org/licenses/by/4.0/). - The files "Exported Qualtrics survey for Stage 1 R1.docx" and "Appendix covering changes to BCTI R1.docx" contain survey items adapted from Swami et al. (2017, https://doi.org/10.1371/journal.pone.0172617), likewise originally shared using a CC-BY-4.0 licence. - The file "Bork method function.R" contains a script which is adapted from Appendix A van Bork et al. (2019, https://doi.org/10.1080/00273171.2019.1672515). van Bork et al.'s article was originally shared using a Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence (https://creativecommons.org/licenses/by-nc-nd/4.0/), with copyright to the authors. However, Dr van Bork provided emailed approval on 13 July 2021 for this script to be distributed, so it is included here.