Statistical analysis
We used R (v4.2.1; R Core Team 2021) and RStudio (version 2023.3.0.386;
Posit Team 2023) to carry out the statistical analysis. All data was
checked for the presence of significant outliers and we used linear
models to assess linearity, distribution of residuals and homogeneity of
variance. Unless otherwise stated, no statistically significant outliers
were detected and all data met assumptions of linearity, homogeneity of
variance and normal distribution of residuals, and two-tailed
correlations were tested with Pearson’s correlation coefficient. We used
cluster-based permutation testing, using the “permutes” (Voeten, 2022)
and “permuco” (Frossard, 2021) packages, to analyse instantaneous
alpha. 5000 permutations of randomly shuffled data were used to create a
distribution of cluster sizes expected under the null- hypothesis.
Clusters of real data that exceeded the 95thpercentile of this null distribution were deemed statistically
significant.