Can you use your iPhone in lieu of your iPad as a data collection device? Yes, as long as the document to be viewed can be seen without having to squint. An iPhone is large enough to fill out a document as long as you hold it in landscape versus portrait mode. See the the same document below when it is displayed on an iPhone 6+ in both portrait and landscape modes. You will notice that less of the document displays in landscape but the text is much larger and requires more scrolling whereas more of the document displays in portrait but the text is a lot smaller to view.
Landscape Mode:
Portrait Mode:
