A doctor’s review of rounds with an iPad

There's a third optimization at work, for small size, both for its own sake and as a byproduct of optimizing for writing speed. Less ink tends to be faster.

Tufte frequently mentions the importance of saving ink when drawing charts, going as far as the rule of thumb that if any line can be erased without changing the meaning of the chart, the chart is better after doing so. But of course, it's not really about saving ink itself, it's just that total ink is a good proxy for the presence of distractions that impair clarity (chartjunk).

Similarly, fast-to-write notes like the fishbone also tend to be fast for trained practitioners to read at a glance. Though they may not be exactly what we'd come up with if starting from scratch with reading speed as the sole criterion, they get much closer than the typical lab results report.

Current electronic alternatives tend to be optimized for something else entirely: ease of printing on a fixed-pitch line printer. We can improve readability greatly by broadening the formatting options beyond that, to include options previously only possible with freeform pen and paper.

An ideal layout optimized for readers and free from obsolete constraints (such as writing speed and legacy print engines) would probably abbreviate fewer words compared to handwritten notes, because unusual abbreviations slow down the reader. At the same time, it would get rid of common words that ended up being frequently repeated on computer reports (medjunk). It could include better graphical and formatting cues (selective boldfacing, symbols, sparklines, spatial layouts like fishbones, etc.)

We can also take advantage of handheld devices like the iPad to allow trends and ranges to be brought up by tapping on a result, instead of trying to display everything all at once.

The fishbones won in the wild against all competitors over a long period of time (decades), and in times when the data-ink ratio was at a premium (because it came from a pen, pushed by a doctor's fist). Now ink (computer printing) is cheap, but that is no reason at all to start reducing the data-ink ratio. It is a reason to look even harder at the practices of the past that used ink most efficiently. Mainly because that efficient use of ink almost universally leads to more data in the eye-span, which inherently leads to better thinking.

Maintaining a high data-ink ratio is probably Tufte's greatest explicit contribution to design. One of his great implicit lessons is to look to the past for examples of great use of ink: the more valuable ink was, the smarter it was used it.

And caliber of thought is the primary concern. Always.

Both the iPhone 4G and the HTC Evo are plays for doctor's money. The larger or more detailed screens of these devices can still fit in coat pockets.