While publishing an iPad app can be profitable, it can also be difficult.

Popular Science was one of the first consumer magazines to publish an iPad app (and the subject of this week’s Case Study on Subscription Site Insider). As pioneers in the industry, they’ve been there for single copy sales, the introduction of app subscriptions, and the introduction of trials and the marketing “opt-in” feature.

While the marketing opt-in, which extends a trial offer or gives subscribers a certain free period, can be great for getting customer data from Apple, Popular Science found that free trial offers were not great for conversion.

So instead, PopSci created a 80-page composite or sample issue, highlighting some of their best work and most innovative digital enhancements. The content is not exactly timely in the sample issue, but its best for highlighting the particular bells and whistles of PopSci’s iPad app — from video to 3D animation.

PopSci told us that the sample issue was a much better conversion tool. And they reiterated findings we wrote about last week: the native app gets a much higher conversion rate than the digital replicas of the print magazine available on Kindle, Nook and Zinio.

But PopSci also struggles with Apple’s opacity regarding customer behavior and data. To read about their work-arounds, and other pricing and content tactics that helped PopSci make more than $1.5 million through its iPad app, read the full Case Study on Subscription Site Insider.