Fig. 5: Cultural revolutions: frequency variables.
From: On revolutions
a pop music: Billboard Hot 100, USA; b newborn girls’ names, USA; c BMJ articles; d English, Irish and American novels. Top row of each series. Trends of frequencies shown as stacked area plots. Middle row. The rate of change index, \({R}_{t}\). Bottom row. Identifying revolutions by Foote novelty. Each cell represents the \({F}_{t}^{k}\) estimate for a given half-width, k and time point; the color of the cell gives the relative \({F}_{t}^{k}\) value, light gray being low and dark gray being high. Note that this color scale is only comparable within any given plot. Statistically significant (\(\alpha\,=\,0.05/2\)) revolutionary periods are overlain in red; conservative periods in blue; when necessary Foote novelty tests were done on differences.
