A/B, MVT testing and usability

Written on 30 March 2015, 10:31pm

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Some quick notes after reading A field guide to usability testing and re-reading the Smashing Book #1:

1. A/B testing

– always test both versions simultaneously
– wait for it :) (use a calculator to determine when to end it, and don’t give up earlier)
– keep the A/B tests for new visitors only (don’t surprise the regulars)
– but make sure that a new visitor gets the same version on consecutive visits
– be consistent: make sure that the variation appears on all pages (ex – if you have a promotional price on version A, make sure that the user will always see the promotional price on all the pages)
– the results might be un-intuitive
– naturally, the higher the number of users, the more reliable the result
More

Who would be involved in an A/B test:
the UI/UX team – to propose the 2 versions and analyze the metric results
the dev team – to implement the metric, manage sessions and make changes consistent across all the interfaces
the network team – to handle various types of redirects (ex – run the A/B test only for users in a given geographical area, or only users on mobile)

2. MVT (multi variate testing)

– it needs a lot of traffic and time
– keep the number of combinations to 25 or less and make sure you preview them all
– global vs local optimum (A/B vs MVT)
– if you don’t have the traffic and cannot use full factorial testing, you can still use partial factorial testing.

3. Some usability rules/principles

(more…)

Human motivation

Written on 30 March 2015, 03:46pm

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Two years ago I was posting 2 Ted talks having as central idea doing the things you believe in. I recently reviewed them and reflected more about the second – called ‘The puzzle of motivation‘ where Dan Pink makes a case on how the current types of activities we’re involved in require different types of incentives.
Dan Pink sees a mismatch between what science knows and what business does: even though there is scientific proof that creative jobs do not work well with rewards, the current business model works just like that.
There are a few exceptions, like the Google initiative to allow his employees to spend one day per week working on an independent project, Atlassian’s FedEx days or – most powerful example – how Wikipedia succeeded and Microsoft Encarta failed:

Encarta’s closing is widely attributed to competition from the much larger online encyclopedia, Wikipedia
Wikipedia page about Encarta (!)

Dan Pink identifies 3 building blocks of an entirely new operating system for our businesses:
Autonomy – the urge to direct our own lives
Mastery – the desire to get better and better at something that matters
Purpose – the yearning to do what we do in the service of something larger than ourselves.

If we bring our motivation, notions of motivation into the 21st century, if we get past this lazy, dangerous, ideology of carrots and sticks, we can strengthen our businesses, we can solve a lot of those candle problems, and maybe, maybe — we can change the world.

More:
* What motivates us
* The Motivation Trifecta: Autonomy, Mastery, and Purpose

PKI in 5 lines

Written on 24 March 2015, 11:28am

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User 1 (Alice): generates private and public key, stores her private key in a secure location, sends the physical data to Registration Authority (RA) for verification
Registration Authority: verifies the user data and informs the Certification Authority (CA)
CA (the trusted authority): signs the Alice public key with its own private key (issuing a digital certificate) and publishes it
User 2 (Bob): looks up the Alice public key and verifies its authenticity with the CA
Communication: Bob sends Alice a message by encrypting it with Alice public key


At this stage Bob knows that the public key that he sees is really the one of Alice. But is it really Alice he is talking to? Here is how to find out:
– Bob asks Alice to encrypt for her a random message
– Alice encrypts this message with her private key
– Bob decrypts this with the Alice public key (which he knows it belongs to Alice because he trusts the CA)
– if the decrypted message is the same as Bob sent, then it must be really Alice herself
And this is how every SSL conversation begins :)

PKI in plain English (PPT, 0.7M)