1 Validation of a Novel Climate Change Denial Measure Using Item Response Theory Mr. George Lorama*,, Dr. Mathew Linga, Mr. Andrew Heada, Dr. Edward J.R. Clarkeb a Deakin University, Geelong, Australia, Misinformation Lab, School of Psychology b Federation University, Mount Helen, Australia, School of Health and Life Sciences * Corresponding Author, Misinformation Lab, Deakin University, Locked Bag 20001, Geelong VIC 3220, Australia. Email address:
[email protected] Declarations of Interest: All authors declare that no conflict of interest exists. Acknowledgements: This work was supported by Deakin University (4th Year Student Research Funding; 4th Year Publication Award). 2 Abstract Climate change denial persists despite overwhelming scientific consensus on the issue. However, the rates of denial reported in the literature are inconsistent, potentially as a function of ad hoc measurement of denial. This further impacts on interpretability and integration of research. This study aims to create a standardised measure of climate change denial using Item Response Theory (IRT). The measure was created by pooling items from existing denial measures, and was administered to a U.S. sample recruited using Amazon MTurk (N = 206). Participants responded to the prototype measure as well as being measured on a number of constructs that have been shown to correlate with climate change denial (authoritarianism, social dominance orientation, mistrust in scientists, and conspiracist beliefs). Item characteristics were calculated using a 2-parameter IRT model. After screening out poorly discriminating and redundant items, the scale contained eight items. Discrimination indices were high, ranging from 2.254 to 30.839, but item difficulties ranged from 0.437 to 1.167, capturing a relatively narrow band of climate change denial.