I analyzed the chords to 1300 popular songs for patterns. This is what I found.

Keep in mind that, with a capo, any key becomes trivial for a guitar.

I tend to agree, but when you think of it, D major isn't used that much in popular music. When you talk about country or acoustic guitar, sure, but not so much in the Billboard charts.

He doesn't go nearly enough into depth to say anything surprising. That "C/Am" is by far the most common is not surprising at all; C major is the first key any music student learns.

I wish he separated out the major keys from minor keys. It's easy to tell the difference; almost no-one writes pop music in the natural minor (which shares a key signature with the relative major), as it has no dominant fifth. Rather, melodic and harmonic minor keys are used, which have a distinct key signature from major keys (both have the 7th note of the scale raised to accommodate a dominant fifth chord). This should make them easy to detect.

The "Chord Use" chart also does not say much; C, F, and G are the I, IV, and V chords of the key of C major (the Roman numerals indicating their relative position in the scale), which together form the basic pop progression. Much more useful would have been to bin the chords relative to the key in which the song is written, rather than as their absolute pitch.

What I would also like to see is a histogram of chord progressions, e.g. I-IV-V vs. I-IV-ii-V vs. I-vi-VI-V etc. His preview of next week hints at this, but again he should use relative chord names rather than absolute chord names.

The preview graph, "Chords following em", is not very surprising either. Since this is an absolute chart rather than a relative one, we must assume that the data is reflective of the chord's use in the most common key (C). (Em will rarely occur in a song written in Am; rather, it will be altered to an E7 dominant chord.) Of the other chords available in the key of C, C and G both share two out of three notes with Em and thus are unlikely to be used due to lack of motion between them. Bdim is rarely used in C.

This leaves Dm, F, and Am as likely to occur following an Em. The E and B notes of the Em chord are a half-step below the next higher note in the scale, so they will tend toward upward motion, meaning the next chord will likely contain an F or a C. F contains both of these, hence its prominence in the graph. Both Am and Dm contain one of these notes; however Em->Am is an upward (downward) skip of a fourth (fifth), which is a resolving motion – it is likely that the next few chords following these two will be Dm, G, and C, to continue this motion. Em->Dm, being a skip of a second, does not share this property and hence should not be as common.

Reason: It's easier to play these chords on a 6 string guitar, which has been the dominant instrument of choice for pop song composers.

The first C chord on a guitar is easy to hit with no finger twisting required. It's also easy to switch between the first C, Am, and G chord, you can even do it quickly and repeatedly while drunk as you can imagine many pop songs are written. The first F chord requires a little more careful finger placement but still easy to get too. Sure enough you hear this over and over in pop songs, some simple sequence of C F G A chords over and over.

Not surprising that the complex guitar chords that require six pencil-thin rubber fingers and a degree in music theory to know how to play aren't heard as often.

Very good analysis. I wasn't even going to comment, since my reaction (personal impression) to the article was "too bad there might be 2 of the 1300 songs that have chords that don't sound like crap" - since they all do, there might be a couple of dozen well-orchestrated popular songs over the last several decades. (I should add that, despite this fact, I do avidly listen to popular songs and don't have a problem. I wouldn't try to reverse engineer their chord patterns though...)

At least your response tells me why this is the case. Thanks!