On finding the (im)perfect iPad stylus

When the iPad was released four years ago last month, my wife got one right away, while I, with uncharacteristic patience, waited until the Fall. Fast forward two years, and we both upgraded to 3rd-gen devices. Early on in that first two-year stretch, I bought the odd stylus or two. In hindsight, “odd” may be the operative word. The first one I got was a Pogo Sketch with its unique foam tip. Within a year, I threw it away. If this seems a harsh judgment, here is advice from one of the developers at Notes Plus, the handwriting app: “avoid it like the plague.” The second stylus I got was from Boxwave, a functional if unimaginative design. I gave it away with the original iPad.

At the time of the iPad’s release, Steve Jobs famously declared, “If you see a stylus, they blew it.” Nonetheless, as the tablet market and stylus competition have expanded, it requires almost as little thought to buy another stylus as it does to buy another app, though it certainly requires more money. Each new one that I got had a design element, or in a few cases a totally new technology, that promised improvement over the ones I already had. Rather than just being a grass-is-greener phenomenon, to a considerable extent that promise proved true. The perfect stylus, however, has remained elusive. (And just to be clear, it will remain so until Apple changes the fundamental underlying screen technology so that a much smaller contact area for a stylus tip is possible.)

Here, in alphabetical rather than chronological order, is my current collection:
* AluPen (JustMobile)
* Apex (LYNKtec) [Active, non-Bluetooth]
* Bamboo (Wacom)
* Cosmonaut (Studio Neat)
* Estylo (NYON)
* Hand (HAND Design)
* Jot Pro (Adonit)
* Maglus (Applydea)
* oStylus (oStylus Design Studio)
* Pad Pen (Playsam)
* Pencil (FiftyThree) [Bluetooth]
* TruGlide Pro (LYNKtec)

There are two others, both Bluetooth-enabled, that I might consider purchasing, but only if/when my current note-taking app of choice, Notes Plus, supports them: Intuos Creative (Wacom) and Jot Script (Adonit).

There are many comparative reviews available online that provide overlapping coverage of most of the dozen in the bulleted list above (but not the Estylo and Pad Pen), of which the following are notable:
* Ellis Hamburger in The Verge (Apr 10, 2012)
* Brandon Widder in Digital Trends (Jan 6, 2013)
* Karissa Bell in The Wirecutter (Jul 17, 2013)
* Yaara Lancet in makeuseof (Aug 27, 2013)
* Serenity Caldwell in TechHive (Nov 26, 2013)

Since my goal here is not a review per se, suffice to say that each stylus has some positive feature(s), or I would not have kept it. But each also has some less salutary feature(s). The things that have gotten the most attention and complaints in reviews, blogs, and online forums are predictably techie:
* tip material — soft rubber (most), hard rubber (Apex), mesh (TruGlide Pro), or disk (Jot Pro, oStylus) — and capacitive behavior; and
* force/precision of screen interaction — there is probably some dependence here on the particular app being used, though the “clicking” on the glass of the disk-based styluses and the Estylo is annoying to many users (including me).


Both of these topics have parallels in the world of fountain pens, of which I am a long-time devotee. Just substitute 14 or 18 kt gold or titanium or steel for the list of tip materials above, and you have fountain pen lovers talking about nibs. Then there is the matter of how much pressure to apply and how well different papers will respond. And we haven’t even gotten to inks yet! This is a fanatical world, much more fanatical than anything most users of an iPad and a beloved stylus can imagine. But it is also a world from which some insight might be forthcoming.

A fundamental consideration for fountain pen users that only merits passing mention in the discussion of styluses is their basic ergonomics. Simply asked, how does a stylus feel and fit in your hand? To address this issue, I have made some modest observations and measurements on eleven of the styluses in the bulleted list. (I omitted the oStylus, which looks and feels much more akin to the Nomad Brush and the Sensu Brush than to any of the other styluses.) Here is a tabulation for weight, length, and cross-sectional shape of those eleven:

Styluswt (g)l (mm)cross-section shape
Estylo4143rnd. square
Jot Pro23127circle
Maglus34130trunc. circle
Pad Pen37115triangle
Pencil24138rnd. rectangle
TruGlide Pro15120circle

Initially, there was nothing in these results that jumped out at me. The modal cross-section, for example, is a circle (five of the styluses); there are six different shapes in total, but none of them seems to suggest a clear winner in combination with the other pro/con features. With fountain pens, I gravitate to larger, which usually means both longer and heavier, all other things being equal. Among the styluses, I like a couple of the heavier ones, but they are not particularly long. Plus there are the seemingly anomalous values for the Estylo, which is by far the lightest, but also the longest. Mostly on whim (meaning, I was just screwing around in Excel where I had the numbers stored), but also because I was curious about the Estylo “anomaly,” I made a plot of weight vs. length:


There is actually a surprisingly good inverse correlation — as weight goes up, length goes down, with a correlation coefficient (R) of 0.468. There aren’t actually a lot of things in the world that work this way, because larger things generally require more matter to construct, which means weight goes up with length, not the other way around. (If people generally worked this way, then LeBron James would more likely be 6’8″ and 150 lbs, instead of his actual 6’8″ and 250 lbs.) As for this correlation meaning anything, well, presumably not.

I showed this graph to my wife, who earns her living with numbers and statistics. She agreed that the R value was interesting, even provocative, but then so is Tyler Vigen’s recently-discovered spurious correlation (R = 0.993) between the divorce rate in Maine and the per capita consumption of margarine in the US. OK then.

I put this all aside, with no particular plan that I would come back to it, let alone write this blog post. Then two things happened: Firstly, I started using the Pad Pen, which had only arrived from Sweden very recently,padpen_white and found that I liked it. It was a little too short to feel like I had a secure grip on it, but it was right up there in weight with two of my other favorites (Maglus, Cosmonaut). Perhaps most importantly, its triangular cross-section was very comfortable and natural-feeling. I even wrote an email to Carl Zedig at Playsam, with whom I had had some correspondence prior to my purchase, telling him how much I like the Pad Pen and how much more I would like it if it were just a bit longer, “even as little as 5-10 mm,” I wrote.

Secondly, all this made me realize that I had never actually looked on the graph at the position of my four favorites, the ones that get 99+% of the usage. I still don’t know why I hadn’t done that before, but now I did, with Pencil, Apex, Maglus, and Cosmonaut (left-to-right) marked as red squares:


If the first graph showed a surprisingly good correlation, this one is staggeringly good. The first R, 0.468, is something that could readily turn up in looking at human behavior, more-than-suggestive but not particularly compelling. But the second R, 0.99969, which I show to more places than the data justify, is perilously close to one (1.0), the kind of value that usually shows up in the lab sciences only in running a calibration curve with known standard materials. Or maybe in repeating your Higgs boson discovery.

Having said that, it’s still only a correlation. There is no hint of causation: I wasn’t testing any hypothesis (which is the essence of science), because I didn’t have one. I still don’t. But I do have to wonder if somebody else has one. Somebody in a biomechanics or ergonomics lab who has looked at how the human hand holds a writing instrument, say, a fountain pen or a stylus. And who understands what the trade-offs are between weight and length of those instruments for a particular hand, say, mine, which might not be the same as for yours. Maybe even somebody who would recognize that I had merely reproduced a well-known pattern. Probably not, but still, it would be fun if it turned out to be true.

In the mean time, I can use the empirical correlation for my four favorite red data points and calculate that I would be very, very happy indeed with a Pad Pen that was 12 mm longer, which would move it straight up to that curve (ignoring the necessary weight change for the same component materials). Closer yet to the perfect stylus, if only for me.

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