For the classical music lovers out there, I’ve done an analysis of key signatures using the compositions of ten composers (Bach, Beethoven, Brahms, Dvorak, Haydn, Liszt, Mendelssohn, Mozart, Rachmoninoff, and Tchaikovsky). I exported their lists of works from the data source listed below, and extracted all the keys of the pieces; if a piece was in more than one key, I used the initial key. Also, enharmonic keys (e.g., A# and B♭) were summed together. I then normalized each composer’s list to find the percentage of pieces he wrote in each key. The lists aren’t comprehensive, but the N values range from 185 to 895, so the sample sizes are good enough for this type of analysis.
For the top graph, I’ve summed and averaged the percentages across the ten composers to show that they have a slight preference for simple keys (fewer accidentals). Note that, on the “total” version (summed), the low percentage corresponding to zero accidentals is not surprising as there are only two keys with zero (C major and A minor) - there are also only two keys with six accidentals (F# major/D# minor) - while the other accidental numbers all have four possible keys (e.g., two accidentals would include D and B♭ major and G and B minor). To remove this effect, I’ve also plotted the average percentage (lower line), which shows zero accidentals as the highest value (likely because both C major and A minor are common keys).
The lower graph was made by taking the average percentage of each key and plotting each major key (plotted on the x-axis) against its relative minor (y-axis). I’ve labeled the points so you can see how common each pair is. Sorry, the number sign was easier to use as a sharp than inserting a ♭ symbol, so everything is in sharp keys. Interestingly, D major is the most common key, but its relative minor (B minor) was quite unpopular (especially with Mozart and Beethoven…more coming on that). Overall, major keys tend to be more common than their relative minors, but not always (F#/d#). D minor wins the award for most used minor key. I guess composers just like D/d…
As I hinted in the previous paragraph, I’m working on another set of plots with these data that will be composer-specific graphics, which will be coming soon.