"In this article, we’ll look at the statistics gathered from 1300 choruses, verses, etc. of popular songs to discover the answer to a few basic questions. First we’ll look at the relative popularity of different chords based on the frequency that they appear in the chord progressions of popular music. Then we’ll begin to look at the relationship that different chords have with one another. For example, if a chord is found in a song, what can we say about the probability for what the next chord will be that comes after it?" - Todd Hoff from Bookmarklet

i also like the keys of A, D and G when writing. mostly this is cos i write on guitar (precludes the key of E flat, for one) and the keys cited fall within my singing range. - Hieronymous Boosh

You can't go too wrong with guessing I, IV, V if you grew up in the West. - Victor Ganata

I wonder if E flat major is relatively more common precisely because it's enharmonic with C minor. - Victor Ganata

Leapin' Lizards, Victor, is there any field you don't know something about? Good lord, you're a polymath. - Spidra Webster

Are there even songs where composers stick isolated D and E chords in a song written in C major? I wonder if he analyzed key changes at all? - Victor Ganata

I'm surprised E-flat/C-minor is as high as it is, given that it's not easy to play on a guitar. I would have thought it would fall below A. Otherwise it's about as I would expect. - John (bird whisperer)

Heh, in this day and age of Wikipedia, I think anyone can be a polymath ;) I think the reeason why I ended up glomming onto music theory was because I really sucked at actual music performance. - Victor Ganata

I think the E-falt major/C minor thing happens because there are two ways you could go when switching from major to minor: stick with the same tonic (C major --> C minor) or stick to the same sharps and flats (C major --> A minor) - Victor Ganata

I'd like to see more inventive structures in music. In classical music we have tons of forms like sonata and minuet and trio. Sometimes I hear popular songs that use ABABA form and it's powerful and distinctive. More of that. - Todd Hoff

Apple's chord choices totally fit with music theory, so I doubt they'd change them to the author's suggestions. They picked iii, vi, ii, V, I, IV, ♭VII, and vii°, all of which would be more common than V/V or V/vi - Victor Ganata

I guess E-flat major/C minor isn't so bad if you use a capo at the first fret and use the chord forms from D major. - John (bird whisperer)

Except then you can't switch back to C major. I imagine this kind of modulation or key change isn't really popular for music played on guitars :D - Victor Ganata