Back in December I said that podcasters should gather and share as much statistical data as possible. It is now exactly three months later and, surprise-surprise, I still feel that way. The topic resurfaced on Saturday when Adam Curry from PodShow posted about the number of download requests the PodShow network has received:

For the record, In December 2006 the network produced 52 million download requests.

Earlier today, Paul Colligan picked up on the story, and said:

Yes, Virginia, Podcast download numbers are important. And these are important numbers.

Yes, they are important. And 52 million is an impressive number, especially for just one month. But stating download requests alone is useless. I think they are important to track, but you need to pair them with something else. Something like a completed download.

Understanding the difference between a download request, a partial download, and a completed download can be somewhat confusing, so let’s try this metaphor on for size.

Download Request = Walking into the grocery store with a shopping list in hand
Partial Download = Filling your shopping cart with some of the items on your list
Completed Download = Filling your shopping cart with everything on your list
Partial Play = Eating some of the things you purchased
Completed Play = Eating everything you purchased

It’s important to note that each one is harder and harder to measure. It’s fairly trivial to count the number of people entering the store. It’s a little harder, but still fairly easy to count the number of people who have at least something in the cart. It’s much harder to count the number of people who have everything on their list. And to count the number of partial and completed plays? Much, much harder.

When you have all of these statistics, you get a really nice picture, don’t you? You can see a nice comparison of how many people entered the store and how many people actually bought something. Having just the number of people who entered the store is not that useful though. Sure it has some useful implications – if tons of people come in but don’t buy, maybe we don’t have what they want, or they didn’t like what they saw, etc. That makes sense in the offline world. In the online world though, it’s not just people that make download requests – it’s other applications and services too. It’s like counting every person, stroller, cart, bag, and box that enters the store – and clearly, only people can purchase something! To make matters worse, some applications will make multiple requests for a single download. Imagine a person walking into the store, putting something in the cart, exiting the store and walking back in again to put the second item in the cart.

So download requests are interesting, but they are really only valuable alongside other information like completed downloads. Or a list of which applications made the requests (this would allow you to tell the difference between a person and a stroller, for instance). Citing just the number of download requests will do nothing but mislead.