Pharrell Williams currently has the number 1 spot on the Billboard Hot 100, for his single "Happy" REUTERS/Mario Anzuoni

Ever wondered what makes a pop music hit? Or what's so refreshing and catchy about the latest No. 1 pop hit? Whether you are an ardent fan or a critic, the recently founded site Musistix could provide you insight into the musical workings of the most popular songs in the world.

Pop music probably isn't the first genre people think of if they're looking to study music, but longtime music teacher Rob Risley has reason to say otherwise. After years of teaching popular songs to his students, Risley became more and more interested in trends in popular music. Last month, he finally decided to plot out musical data on the songs at the top of the charts.

Risley says Musistix "is about taking an analytical approach to the musical elements that make up the top pop songs of the week. Combining statistics and music theory to find trends, outliers, and other interesting details."

Each week, Risley plots the key, chord progression, tempo and meter of the week’s top 20 tracks on the Billboard Hot 100. He doesn't do lyrics yet, but IBTimes Lisa Mahapatra put together an excellent graphic analysis of lyrics in pop music since the 60s, here. Even if you’re not musically trained, Musistix makes it easy to learn more about music.

Musistix is only a month old, but Risley says trends can be studied as it matures. We talked with Risley about Musistix, what he's noticed thus far and his plans for it in the future.

IBTimes: What are some (or one) major trends you’ve noticed so far, if there are any?

Risley: It's hard to say. The site is actually only about a month old, so it's probably too soon to see any major trends. But I've actually been surprised at how much variety I've seen in keys and chord progressions.

One possible trend so far has to do with major vs. minor keys. So far 48 percent of the songs appearing in the top 20 have been in minor keys, but if you look at the top five songs, it's 75 percent minor keys. Sometimes I wonder if minor key songs are more popular in the winter and major keys are more popular in the summer. That's an example of the sort of thing Musistix might be able to investigate over a long enough time period.

IBTimes: What, for you, is the most interesting thing about analyzing pop music?

Risley: The most interesting thing is that even though many of these songs have a lot in common, they still find ways to distinguish themselves. There seems to be a balance between following musical conventions and yet adding an artist's individual style. And every once in a while a song comes along that surprises you by doing something different.

But it's interesting to boil these songs down to basic ingredients and then use that as a starting point for comparison.

Have you noticed anything that suggests certain progressions or practices make for a more popular song?

Risley: So far it seems like tempo makes a bigger difference than I would have thought. The average pop song is around 100 bpm, but lately I've seen a lot of songs that are either much faster (“Happy,” “Timber”) or much slower (“Dark Horse,” “Say Something,” “Drunk in Love”) make it into the top five. Maybe there's a link between popularity and songs with more drastic tempos, but it's hard to tell with the limited data so far.

A lot of people have this idea that pop music lacks musical substance. What are your thoughts on that? Have you been swayed either way since working on Musistix?

Because I teach guitar for a living, I'm used to listening to this kind of music on a daily basis with my students. So I try to stay open-minded. Pop music definitely isn't as complex as other types of music, but it doesn't mean you can't learn from it. Especially if you're a musician just starting out. Analyzing pop songs is a great way to get a grasp of the basics of music theory.

What, in your opinion, makes a good pop hit? Can it really be boiled down to a science?

I think the most important thing a good pop song needs is a hook. There are millions of songs out there trying to get the listener's attention, so what can a song do to really stand out? I think coming up with a good hook is a really inexact science, so I'm really impressed by songwriters who can do it consistently.

I don't necessarily think music can ever be boiled down to a science. My goal with Musistix is to track some of the measurable aspects of music, but it's very difficult or impossible to quantify all the other elements that make a song great like production value, a singer's vocal tone, lyrics, instrumentation, etc.

What are some aspects of music you’d like to incorporate into your analysis on Musistix?

I've thought about tracking things like vocal range, lyrics, and possibly some aspects of melody. Melody is so extremely important to pop music, but it's a ton of work to transcribe and analyze. Right now I try to address those sorts of things that are less measurable in the weekly summary and blog section of the site.

If a reader wanted to write a pop hit, what would you suggest they incorporate into it? (keys, progressions, timing, etc.)

It's definitely tempting to use one of the “go-to” chord progressions like I, V, vi, IV and just keep the song simple. Pop songs are often about taking a very simple and catchy idea and then developing it. The key of the song should really be whatever suits the vocalist best. Other than that, all of these aspects are just a starting point for writing a song.

I think all genres of music have a long history of imitation. It might be more evident in pop music than any other type. So I think beginning songwriters shouldn't be afraid to imitate as long as they find some way to make their song unique in the end.

What's a I V vi IV progression? Trust us, you know it. Watch the Axis of Awesome sing (almost) every popular song that uses one of the most ubiquitous progressions in music: