Validation of a Novel Climate Change Denial Measure Using Item Response Theory

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. Internal consistency was high, ω = .94. Moderate to strong correlations were found between the denial measure and the convergent measures. This measure is a novel and efficient approach to the measurement of climate change denial and includes highly discriminating items that could be used as screening tools. The limited range of item difficulties suggests that different forms of climate change denial may be closer together than previously thought. Future research directions include validating the measure in larger samples, and examining the predictive utility of the measure.