Are Yahoo Mail users better customers than Gmail users?

September 28th, 2013 Comments off

I admit it: I judge you by your email address. Whenever I see a Hotmail, AOL, or Yahoo address, I can’t help but think that somebody didn’t get the memo in the mid-aughts about moving to Gmail.

It’s ridiculous. Somebody is no better or worse of a person for using Hotmail. All a non-Gmail, non-custom, address probably means is that the person is outside of my peer group. And yet the bias remains.

But what if that bias is justified? What if I can tell how good a customer will be based on the customer’s email address?

I run a µISV, in which I develop and sell blur reduction software called Blurity. As such, I have a large collection of purchase data, and that purchase data contains email addresses.

Let’s start with a look at the distribution of email address domain names. I queried the purchase logs for Blurity from October 2012 to find the percentage of purchases associated with each second-level domain name. Domain names that appeared in less than 1% of purchases were consolidated in an “other” group. From that, we can see that Gmail, Yahoo Mail, and Hotmail are the most popular email services for Blurity customers:

Proportions of email address domains for Blurity customers. Domain names representing less than 1% of customers are grouped in “Other.”

Not surprisingly, people also liked holding on to email addresses more commonly associated with ISPs, such as AOL, Comcast, Verizon, BT, and COX. (Time Warner fell just below the 1% threshold and is part of “other.”)

It’s tempting to say that Yahoo Mail is under-represented among customers, since in terms of US email service market share Yahoo Mail is roughly equal with Gmail. However, the share percentages are about equal for international users of the two services, and I couldn’t split my purchase data on international lines. Dead-end there.

So what can we look at? Maybe something to do with money? Well, how about return rates?

Blurity has a somewhat high return rate. Embarrassingly high. I attribute that to a combination of my poor UI design skills and the general misalignment between public perception of blur removal and the reality of blur removal. That, in turn, is complicated by the fact that many people don’t read directions, which is further compounded by people believing that the purchased version will somehow do better blur removal than the free trial version. As a result, I occasionally get emails asking for refunds. It’s the cost of doing business. I’d rather have a happy former customer than an angry customer.

I’d always felt that refund requests were more likely to come from the group of people using email services associated with lower degrees of technical prowess, such as Hotmail and AOL, so I was a bit surprised when I pulled the actual data. Turned out that the refund rate of Gmail users was not significantly different from that of Hotmail users, nor for Gmail versus AOL users.

Yahoo was a different story. The refund rate for Yahoo Mail users was higher than that for Gmail users at a statistically significant level (chi-squared, p<0.05). Found one!

That's enough data to recover the underlying numbers. Or is it?

Return rate by email domain name.

A higher return rate is nothing to celebrate, but it’s always nice to discover data vindicating one’s intuition.

Overall, Gmail was pretty good, or at least average. The only group that had a non-zero return rate significantly lower than Gmail was the “other” bin (chi-sqaured, p<0.01). The rest of the domains, including Hotmail, were all roughly the same, ignoring a few small-sample-size zero counts.

After seeing those results, I wondered what other predictors for refunds I could find in the data. I suspected that customers paying with PayPal might have higher return rates than those paying with Stripe. Maybe it was a manifestation of the general ill-will towards PayPal in the tech community? Much to my surprise, the refund rate for PayPal is actually lower than for Stripe (6.4% vs. 9.5%), though not significantly so.

I’m not sure that this is very actionable. The vast majority of customers of all sorts, including those with Yahoo email addresses, have been fantastic. I might try an A/B test for users entering Yahoo email addresses, perhaps with a more explicit link to the user manual or a tutorial video. Of course, if I think that might work for Yahoo users, then I might as well try it with everybody. Yahoo might have more refund seekers than other services, but it by no means has a monopoly.

Update: Had another customer make a purchase today and then almost immediately (three minutes later) ask for a refund. The customer’s email service? You guessed it: Yahoo.

Update 2: My friend Luke pointed out that the, Hotmail, and MSN domains are really all just Microsoft services. I agree, they should probably be grouped. I ran the numbers again with that grouping and found that the refund rate for the Microsoft properties does not differ significantly from that of Gmail, and the confidence interval is very similar to that charted for Hotmail alone. Thus, the conclusions above remain unchanged. Regardless, a good catch!

Pulp Entrepreneurship

September 16th, 2013 2 comments

With apologies to Quentin Tarantino.

At a table inside the Coupa Cafe, a coffee shop in Palo Alto,
California.  VINCENT and JULES are eating breakfasts of
eggs/sausage/pancakes and a muffin, respectively, and drinking
coffee.  They are talking about entrepreneurship.

        Yeah, I've just been sitting here thinking.

        About what?

        About the startup I've got cooking.

        Startup in your mind.  I think you don't have anything
        more than a weekend hack.  Maybe a web app at best.

        What is a startup, Vincent?

        A company that's just getting going.

        And what kind of company would qualify?

Vincent takes a sip of coffee

        It's... a company that has aspirations of growth, of making
        money, 	of changing things for the better.

Jules points at Vincent to indicate that he's hit on the main idea.
Vincent pauses, and then continues.

        But your little side project, I don't think it qualifies.


        Hey Vincent, can't you see that shit don't matter?  You're
        judging this shit the wrong way.  I mean, it could be that
        my company will hit it big, or that Snapchat won't just be a
        fad, or that some 16-year-old will flip a stupid vampire
        social network to some dumb 18-year-old wannabe hedge fund
        manager.  You don't judge shit like this based on merit. Now
        whether or not what I'm doing is an according-to-Graham
        "startup" is insignificant.  But what is significant is that
        I feel it in here. 

Jules points to his heart.

        I know that what I'm doing is a startup.  Call it what you
        want, but it's a startup to me.

        But why?

        Well, that's what's fucking with me.  I don't know why.  But
        I know it's what I'm meant to do.

Vincent SCOFFS.

        You're serious?  You're really thinking about quitting?

        Software consulting?  


        Most definitely.

        Fuck. You're making such great money!

Vincent SIGHS.

        So what are you going to do then?

        Well, first I'm going to deliver the remaining code to my
        client.  Then, basically I'm just going to do the startup thing.

        What do you mean, "do the startup thing?"

        You know, like Zuckerberg and Facebook. Raise money, write code,
        change the world.  

        And how long do you intend to "raise money and write code"?

        Until my startup takes off and I have a successful exit.

        And what if you never have an exit?

        We're in a bubble.  Somebody will buy it.

        So you decided to be an asshole. 

        I'll just be Jules, Vincent.  That, and I'll be incredibly
        rich eventually.

        No Jules, you decided to be an asshole.  Just like all of
        those pieces of shit writing pretentious blog posts and
        going on about social-this or mobile-that.  Who pretend
        their MBAs qualify them for eight-figure VC investments,
        or who treat content farming like it's adding utility to the
        web.  They have a name for that, Jules: an asshole.  And
        without a revenue plan or a product that will scale that's 
        all you're going to be at your so-called "startup": a 
        fucking asshole.

        Look, my friend, this is just where you and I differ.

        Jules, what happened over the past few days, I agree,
        some angels showed some interest and your stub of a signup
        page collected a few email addresses, but an actual
        startup?  I don't think...

        Any idea as long as it can get traction, Vincent.

        Don't fucking talk that way to me, man.  How will you make

        If my answers frighten you, then you should cease asking
        scary questions.  

        Let me ask you something; when did you make this decision?

        Just recently.  I was sitting at home, reading about how
        Twitter was about to IPO, and how Uber picked up $250 million 
        from Google, and I had what techies refer to as, "a moment 
        of jealousy."


When robots flew

June 25th, 2013 Comments off

I was getting out of my car when a small plane buzzed over my head. Sam was parked in a grass field amongst many other Subarus and SUVs. The clouds above were breaking; it was going to be a hot day in Boulder.

I let my gaze follow the plane as it buzzed down the field. A wide gate was set in the air like a high-jumper’s bar, but instead of going over it, the plane went below it. In the distance, I could hear a roar of approval come up from the crowd of spectators. It would have been a trivial flight maneuver for a human, but no human was at the controls: the plane was flying autonomously.

When I think of robots, I think of autonomy. Sure, remote-controlled devices may technically qualify as robots, but that’s always seemed a bit like cheating to me. Imagine my thrill, then, when I found out that one of the largest competitions for amateur autonomous robot designers would be held an hour from my home in Denver.

The Autonomous Vehicle Competition draws participants from all over the country, and indeed, the world. It’s the effort of Sparkfun, a Boulder company that supplies electronic parts and kits to hobbyists of the robot kind. The competition is split into two different challenges: one requires navigating a ground course, roughly a square 100 ft on a side in a parking lot with obstacles; the other requires flying from a judging area over about 300 feet of water, crossing a peninsula, and returning to the origin. Each run is scored according to navigation time and extra challenges completed.

A ground-course vehicle leaps over the finish line

About a decade ago, my friend Joey and I made a GPS-guided self-driving Lego car for a class project. It was crude and didn’t work very well, but the thrill of having wrought into existence something that could actually drive itself around — well, I was all smiles even back then. The same enthusiasm was written on the faces of the hobbyists and engineers at the competition. I’m sure the same excitement is shared by those people working on the slightly bigger toys at Stanford and Google.

A large crowd of spectators packed the viewing stands and spilled out along the safety fences and grass. They were young and old, overwhelmingly male but not wholly without female representation. Some were entrants waiting for future heats; others were simply there for a passive thrill.

I spent some timing watching the aerial competition before moving to the ground track. Much to my surprise, the plane I had viewed upon my arrival was one of just a few fixed-wing entries. Though there was one true helicopter in the mix, the vast majority of aerial bots were quad- or octo-copters.

One of many quad-rotor entries; but unlike the others, a successful one

I’ll admit that a certain part of me wanted to see a big splash in the aerial competition, but that didn’t happen: the designs were surprisingly resilient, albeit not often successful. Also, the makers were generally standing by ready to cut over to manual control should everything go sideways.

Some entries ran the course and chalked up bonus points without breaking an electronic sweat; others failed to do much more than lift off the deck, hover for a few seconds, and set back down.

Over at the ground competition, the range of entries was a diverse affair. Everything from self-balancing two-wheeled contraptions the size of a coffee cup to a big-wheel tricycle made attempts on the course.

A “big wheel” is chased by a mini Segway

The course proved deceptively difficult. Very few of the ground vehicles successfully navigated the circuit. For at least half the entries, that meant failing to make the first of the four turns.

Some bots slammed into the far fence. Others turned too soon. A couple spun around at the starting line and zoomed off at high speed the wrong way around the course. The defending champion’s bot got loose in the infield, leading to a college-age nerdy guy running as fast as he could to chase it down, with the bot swerving to and fro as if it were trying desperately to escape some tyrannical master.

Spectators, spectators everywhere

Oh, and crashes! During the unlimited-class heat, I got to see the carnage I had paid (nothing) for: one smallish slammed itself into the far fence. Meanwhile, a large gas-powered go-kart bot gained speed off the starting line, started going for the first turn, and then apparently decided to give it a miss and accelerate into the fence — right where the small bot was hung up! The go-kart tried to get away and dragged the small bot a good 20 feet down the fence, leaving bent wire and miscellaneous bits of expensive plastic in its wake.

Crashes! A go-kart takes out a smaller bot, much to the amusement of the non-owners

During a lull in the competition, I took a walk through the team pit tent. At table after table, teams (and they were teams — I saw almost no solo entries) were hunched over laptops, sifting through telemetry, tweaking code, and mending broken bot bodies. The people were as dedicated as any I’ve seen in any other competition.

A college-age man works on his robot in the pit tent

And yet, the mood remained light. There was an overwhelming air of fun and excitement. Even the entrants whose bots had failed wore big smiles as they carried their creations off the course and developed stories of what went wrong and how the big victory got away. Fishing stories are not just for fishing.

Entries ranged from the simple (an 8-year-old boy made it half-way around the track with a Mindstorms-based four-wheeled bot) to the ultra-sophisticated (the university quad-copter teams running using GPS, computer vision, and other whiz-bang gadgetry). Complexity seemed to be poorly correlated to success, at least on the ground course: the slow and steady bots, apparently using dead-reckoning, generally performed more reliably than their fancier, faster, GPS-enabled, optical-sensor-encrusted cousins.

This young girl’s robot had no shortage of anthropomorphic flare

I felt more inspired than ever to make an entry for next year. How hard could it be?


My web browser’s view of me

April 7th, 2013 Comments off

What does your web browser think you like?

Many modern browsers, including Google Chrome, have a nifty predictive-text feature in the address bar.  You start typing, and it predicts what you’re trying to say. This works even after a single letter. The results are shaped to each individual based on one’s browsing and search histories.

So, I got to thinking: which web sites does Chrome predict for me for each letter of the alphabet?

Here’s what I found: (I recently got an Amazon Prime subscription, and it’s pretty awesome) (I like the classic interface much better than the “normal” one) (A bit of a surprise, as I haven’t bought or sold anything on eBay in a while) (Best travel search site at the moment) (I sell some stock photos here. I also seem not to visit many other “i” sites) (I must not visit many “j” sites either) (Still searching for love!) (About 30% of Blurity purchases are via PayPal) (Very surprised by this one — I think I’ve been here once in the past year, and the site isn’t even all that useful) (Google is better for searching patents, and is better for viewing them, but only here can I view the PAIR data) (Per my records, the last time I bought something from Zappos was August 2007)


Based on this data, what picture can we draw of me?  Maybe that I’m a tech-savvy engineer who likes to travel, laugh, keep up with friends, and buy and sell things on the internet?

The problem with this data is that it is not directly correlated to the frequency of visits. For that, it’s more useful to look at Chrome’s “Most Visited” sites, visible when a new empty tab is created.

Thumbnails of the thumbnails of my frequently visited sites

For me, the sites are:


Curiously, two of the entries on this list (CNN and Craigslist) were absent on the predictive list. This gets at a second problem with predictive input: it doesn’t work as well when there are multiple sites that start with the same letter or sequence of letters.

I wonder how self-reinforcing these sets of sites are. That is, am I more likely to continue to visit them because the effort required to change is higher than to not change?  It’s possible.

CNN in particular might be an example of that. Most of what they publish comes from the wires, so I could just as easily make something like the Denver Post or Reuters my hard-news mainstay. In fact, I’ve done exactly that on my phone. Still, the motivation to switch on my desktop computers is lacking.

It should be interesting to see how this changes over time. I expect that Hacker News, Wells Fargo, and Blurity will stay on the list for the foreseeable future. OkCupid may drop out if I manage to find that special guy. And Facebook? It’s an unknown. Will I still care about it in four years? Not sure. The next shiny thing might have come to the fore by then.

Through the past 16 years

January 28th, 2013 Comments off

In light of the recent NPR piece on one’s perception of one’s own change over time, I thought I’d pull together a gallery of my identification cards from the past 16 years.

Let’s start off by showing how nerdy I looked as a teenager. Perhaps you thought you looked nerdy, but I think I won this battle.

My 15-year-old self. What a nerd! Also, my adorably outdated signature; apparently, I still signed my name in a somewhat legible manner when I was 15.

It turns out that there was another option for the lede photo: my first high school ID. If anything, I look even dorkier there.

Time for high school.

You might expect that my first year of high school would have knocked some style or self-awareness into my head. Nope. Near the end of my sophomore year I got my driver’s license, and I was looking as nerdy as ever.

First driver’s license. If you look closely, you can tell that this is a different photo than was on my learner’s permit.


Or perhaps not. The first signs of a stylistic thaw emerged at the beginning of my junior year. I seem to have learned that the top button of a shirt should remain unbuttoned.

Slightly less nerdy? That said, I was wearing a polo shirt from Philmont, which wasn’t exactly the epitome of high-school cool.

Then it came time for senior year. My eyes were still squinty, but it seems that I was making an effort. No glasses (at least for the photo), a t-shirt under my polo shirt, and a chin-up pose that seemed to scream optimism.

My first ID without glasses, even though I was still wearing glasses at the time.

When I went off to college, 600 miles from home, I recognized it as an opportunity for reinvention. Nobody knew me at Rose-Hulman; I could be whomever I wanted to be. I resolved to be more outgoing, to challenge myself more, and to leave college with no regrets.

For the first time in any of my ID photos, the whites of my eyes are visible.

You can’t see it in this photo, because again I took my glasses off before sitting, but by the start of undergrad I had switched to less dorky frames.

Between the time I got my Rose-Hulman student ID and the time I got my next driver’s license, I gained about 15 lbs and then lost about 20 lbs.

A proper photo for my 21st birthday! No glasses anymore, just contact lenses. The signature on my ID is amusingly inaccurate, possibly because of a poor digitization.

My first passport was issued in the era where one could smile in one’s photos.  That was fine. The bigger problem with my first passport photo is that I took it myself by holding a digital camera at arm’s length. The resulting foreshortening distorted my face, giving me a big nose.

…and then we take a step backwards for my first passport.

As with my passport, I supplied my own photo for my Stanford student ID. A few things are notable. First, I was aware of foreshortening by that time, so I didn’t repeat the big-nose mistake. Second, I had been working on losing weight, so I weighed only 175 pounds at the time (March 2007). Finally, I kept taking photos until I ended up with one that I thought looked good rather than one that was a typical representation of myself.

Stanford allowed students to supply their own photos, so I did.

It’s easy to get carried away when taking one’s own photos. I had an internal perception of myself, and when my prospective Stanford ID photo didn’t reflect that, I decided that the photo needed fixing, not me. A few spots of acne? Easily cloned out. Spent too much time inside? Fiddle with the curves to grant a nice tan. Eyes too dark? Dodge them, and maybe make the whites whiter at the same time.

Although the person in the photo is recognizably me, I know from observing others who have resorted to similar trickery that the end result rings false to the outside world.  Self-perception is as we wish we were, not as we are.

I carried my Stanford ID until long after I should have done away with it. When faced with a profound life transition, we tend to hang on to the familiar past, even when we know we should be moving forward. I’ve watched myself do it numerous times, and I expect I will do the same in the future. I wonder if such transitions are more difficult for the younger generations, what with the rise of social networks, texting, and the like?

I had reason to be smiling in my next Minnesota driver’s license: I was about to leave for grad school in sunny California.

Sharp-eyed readers will notice that my claimed height dropped an inch for this license. I don’t think I ever really was 6’1″ — that was merely wishful thinking. I am, however, a full 6’0″ tall. I decided to own up to the deception in my new license.

Definitely getting a bit older for my 25th.

And then, there’s a long gap in new photos. I was a Minnesota resident for a while, and Minnesota takes new driver’s license photos only every five years. That meant that my photo from 2007 was automatically applied to the face of my renewed license in 2011.

Was that the end? No. I moved to Colorado in 2012, so there was another ID to get! Specifically, a rather fake-looking Colorado driver’s license.

Not a huge fan of this photo. C’est la vie.

I also had to replace my passport. Aware of the deficiencies in my Stanford ID photo, I settled on a journalistic aesthetic for my likeness on my new passport.

I stood in front of a wall and asked Tyler to snap a photo. The only light was supplied naturally through a large window.  Did I fix my cheeks, reddened from skiing? Did I enhance the blue in my eyes? Did I pull my hairline down my forehead a bit? No. Post-production consisted solely of snapping the background to white.

Photo for my new passport. Note my red wind-chapped cheeks from skiing.

Looking back through the photos, it’s clear that I’ve aged. What the photos don’t show is my evolution as a person. I went from not knowing how to skate to playing hockey all over the continent. I found my political ideals shifting towards the center, a transition hastened — strangely enough — by my time at Stanford. I learned that I, too, was mortal, after watching my cousin Nick, two years my junior, die in the line of duty.  And, of course, I’ve become comfortable enough with myself and the cultural climate to admit to the world that I’m gay.

Evolution as a person keeps one interesting to others. There is a balance to be maintained — become too different, and friends from the past might drift away — but stagnation serves nobody well.

It will be interesting to see how I continue to evolve in the next decade and a half. What interests will I develop? Who will I meet? Where will I live? What heartaches will I endure? There is certainty only insofar as there is uncertainty. I’m excited to see how the journey unfolds, into the unknown.