Vincent Gable’s Blog

January 17, 2009

Lessons From Fast Food: Efficiency Matters

Filed under: Design,Programming,Quotes,Research,Usability | , ,
― Vincent Gable on January 17, 2009

Every six seconds of improvement in speed of service amounts to typically a 1% increase in sales. And it has a dramatic impact on the bottom line.

–John Ludutsky, President of Phase Research, quoted on the “Fast Food Tech” episode of Modern Marvels, aired 2007-12-29 on the History Channel.

I wouldn’t expect things to be much different in the software world. The faster you get your burger bits the better.

UPDATED: 2009-02-05:
Apparently people want service much faster from software. Greg Linden reports,

Half a second delay caused a 20% drop in traffic. Half a second delay killed user satisfaction.

This conclusion may be surprising — people notice a half second delay? — but we had a similar experience at Amazon.com. In A/B tests, we tried delaying the page in increments of 100 milliseconds and found that even very small delays would result in substantial and costly drops in revenue.

If the Mr Ludutsky’s figure is accurate, a 20% drop in fast-food revenue would require a two minute delay. Does this mean every second spent waiting on a computer is as bad as waiting 4 minutes in meatspace? I don’t know — I’m doing a lot of extrapolation from hearsay. But it’s something to consider.

January 16, 2009

Economic Distress and Fear

Filed under: Quotes | , ,
― Vincent Gable on January 16, 2009

Part of the debtor mentality is a constant, frantically suppressed undercurrent of terror. We have one of the highest debt-to-income ratios in the world, and apparently most of us are two paychecks from the street. Those in power — governments, employers — exploit this, to great effect. Frightened people are obedient — not just physically, but intellectually and emotionally. If your employer tells you to work overtime, and you know that refusing could jeopardize everything you have, then not only do you work the overtime, but you convince yourself that you’re doing it voluntarily, out of loyalty to the company; because the alternative is to acknowledge that you are living in terror. Before you know it, you’ve persuaded yourself that you have a profound emotional attachment to some vast multinational corporation: you’ve indentured not just your working hours, but your entire thought process. The only people who are capable of either unfettered action or unfettered thought are those who — either because they’re heroically brave, or because they’re insane, or because they know themselves to be safe — are free from fear.

Quote is from The Likeness, a novel set in Ireland, by Tana French. (Via Schneier on Security.)

January 14, 2009

Why Work

Filed under: Quotes | ,
― Vincent Gable on January 14, 2009

Psychologists talk about two kinds of motivation: intrinsic and extrinsic. Intrinsic motivation is what drives you to do something regardless of whether you will receive a reward. Why do you spend an hour cleaning the inside of your stove? Nobody looks in there. Your intrinsic motivation compels you to do a thorough job. We all have it — in fact, most people start out with the desire to excel at whatever they do. Extrinsic motivation is the drive to do something precisely because you expect to receive compensation, and it’s the weaker of the two.

The interesting thing, according to psychologists, is that extrinsic motivation has a way of displacing intrinsic motivation. The very act of rewarding workers for a job well done tends to make them think they are doing it solely for the reward; if the reward stops, the good work stops. And if the reward is too low, workers might think, Gosh, this is not worth it. They will forget their innate, intrinsic desire to do good work.

—Joel Spolsky

I’ve quoted Joel before about bad incentive plans.

January 9, 2009

Biometrics

Filed under: Design,Quotes,Research,Security | , , , ,
― Vincent Gable on January 9, 2009

Summary of an article by Bruce Schneier for The Guardian,

Biometrics can vastly improve security, especially when paired with another form of authentication such as passwords. But it’s important to understand their limitations as well as their strengths. On the strength side, biometrics are hard to forge. It’s hard to affix a fake fingerprint to your finger or make your retina look like someone else’s. Some people can mimic voices, and make-up artists can change people’s faces, but these are specialized skills.

On the other hand, biometrics are easy to steal. You leave your fingerprints everywhere you touch, your retinal scan everywhere you look. Regularly, hackers have copied the prints of officials from objects they’ve touched, and posted them on the Internet. …

Biometrics are unique identifiers, but they’re not secrets.

… biometrics work best if the system can verify that the biometric came from the person at the time of verification. The biometric identification system at the gates of the CIA headquarters works because there’s a guard with a large gun making sure no one is trying to fool the system.

One more problem with biometrics: they don’t fail well. Passwords can be changed, but if someone copies your thumbprint, you’re out of luck: you can’t update your thumb. Passwords can be backed up, but if you alter your thumbprint in an accident, you’re stuck. The failures don’t have to be this spectacular: a voice print reader might not recognize someone with a sore throat…

In Why Identity and Authentication Must Remain Distinct, Steve Riley cautions,

Proper biometrics are identity only and will be accompanied, like all good identifiers, by a secret of some kind — a PIN, a private key on a smart card, or, yes, even a password.

January 4, 2009

Conway’s Law

Filed under: Design,Programming,Quotes | , , ,
― Vincent Gable on January 4, 2009

Any organization that designs a system (defined more broadly here than just information systems) will inevitably produce a design whose structure is a copy of the organization’s communication structure.

–Melvin E. Conway

As Wikipedia points out, “Conway’s law was not intended as a joke .. but as a valid sociological observation. It is a consequence of the fact that two software modules A and B cannot interface correctly with each other unless the people who made A communicate with the people who made B. Thus the interface structure of a software system necessarily will show a congruence with the social structure of the organization that produced it.”

How To Beat Web Apps

Filed under: Cocoa,Design,Quotes,Usability | , , ,
― Vincent Gable on January 4, 2009

The way Apple stays ahead of the web app trend is by creating native Cocoa experiences that can’t be duplicated in web apps — both on the Mac and iPhone.

—John Gruber

December 31, 2008

Ellison’s Law

Filed under: Quotes,Security,Usability | , ,
― Vincent Gable on December 31, 2008

Carl Ellison (a cryptographer at Intel, a great guy) formulated what I call Ellison’s Law, which states that the userbase for strong cryptography declines by half with every additional keystroke or mouseclick required to make it work. Think about that when you’re designing tools.

–Cult of the Dead Cow

December 26, 2008

Always Update the View From the Main Thread

Filed under: Announcement,Bug Bite,Cocoa,Interface Builder,MacOSX,Objective-C,Programming,Quotes | , ,
― Vincent Gable on December 26, 2008

I wish I’d read this years ago:

AppKit, the GUI framework, is not thread safe. In order for things to work properly, you (almost) always need to update GUI classes from the main thread

—Dave Dribin (slightly edited)

I’ve run into UI + threading problem before, but I’d just never seen this limitation of AppKit spelled out.

Dave’s article explains how to call code on the main thread better then I can.

December 22, 2008

How To Multi

Filed under: C++,Cocoa,MacOSX,Objective-C,Programming,Quotes | , , , , ,
― Vincent Gable on December 22, 2008

Avoid distributed computing unless your code is going to be run by a single client with a lot of available hardware. Being able to snarf up CPU cycles from idle hardware sitting around in the user’s house sounds cool but just doesn’t pay off most of the time.

Avoid GPGPU on the Mac until Snow Leopard ships unless you have a really good application for it. OpenCL will make GPGPU a lot more practical and flexible, so trying to shoehorn your computationally expensive code into GLSL or CoreImage today just doesn’t seem worth it.

Using multiple processes is a good idea if the subprograms are already written. … If you’re writing your code from scratch, I don’t recommend it unless you have another good reason to write subprocesses, as it’s difficult and the reward just isn’t there.

For multithreading, concentrate on message passing and operations. Multithreading is never easy, but these help greatly to make it simpler and less error prone.

Good OO design will also help a lot here. It’s vastly easier to multithread an app which has already been decomposed into simple objects with well-defined interfaces and loose coupling between them.

—Mike Ash (emphasis mine, line-breaks added). The article has more detail and is very much worth reading.

One point that this advice really drives home for me is that you need to focus on making good code first, and defer micro-optimizations. If taking the time to clean up some code makes it easier to parallelize, then you are optimizing your code by refactoring it, even if at a micro-level you might be making some of it slower by, say, not caching something that takes O(1) time to compute.

Apple does not sell a Mac that’s not multi-core, and even the iPhone has a CPU and a GPU. There’s no question that optimization means parallelization. And all signs point to computers getting more parallel in the future. Any optimization that hurts parallelization is probably a mistake.

December 20, 2008

“Most Windows Developers Couldn’t Care Less About Design”

Filed under: Design,Programming,Quotes | ,
― Vincent Gable on December 20, 2008

Judging by the applications I’ve used, most Windows developers couldn’t care less about design. That’s bad. What’s even worse is learning that same design carelessness has shipped in the box with every copy of Visual Studio since 2002.

See, even Jeff Atwood says it, and he’s no Mac fanboy.

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