15 A/B testing mistakes I see all the damn time (and what to do about it) by Peep Laja, ConversionXL Call to Action Conference 2014

“You should test that!”

“Dude wtf?”

@peeplaja Typical scenario: A company runs 100 tests / year. After 12 months their conversion rate is still the same.

@peeplaja Testing mistake #1: Precious time wasted on stupid tests

@peeplaja Testing mistake #2: You don’t have a data- driven, learning- oriented hypothesis

@peeplaja Testing mistake #3: You think you know what will work

@peeplaja Testing mistake #4: You run tests when you have no traffic

@peeplaja Testing mistake #5: Your absolute conversions are way too low

@peeplaja You need *at least* conversions PER variation. Way more if you want to segment the data

@peeplaja Our "thumb rule" is: conversions per variation and 3-4 week test duration. That is enough traffic so we can even talk about valid data if we drill down into segments. Testing "sin" nr.1: search in segments for uplifts although you have no statistical validity, e.g. 85 versus 97 conversions. That’s bullshit.

@peeplaja Testing mistake #6: Your tests don’t run long enough

@peeplaja Testing mistake #7: You don’t test full weeks at a time

@peeplaja Testing mistake #8: Test data is not sent to third-party analytics

@peeplaja Pro tip: If you have over 500,000 pageviews / mo, you don’t (necessarily) need to spend $100,000 on GA Premium. Get unsampled data with Analytics Canvas

@peeplaja Testing mistake #9: You give up after your first test for a hypothesis fails.

Full case study: conversion/ conversion/ 79.3% uplift in conversions

@peeplaja Testing mistake #11: You’re not aware of validity threats

@peeplaja History effect Instrumentation effect Selection effect

@peeplaja Testing mistake #12: You’re ignoring small gains

@peeplaja 5% monthly increase in your conversion rate will result in 80% uplift for the year. That’s how math works.

@peeplaja Testing mistake #13: You don’t know html/css/jquery - and thus only test the simple stuff

@peeplaja Testing mistake #14: You’re not running tests at all times

@peeplaja Testing mistake #15: You’re late for your lunch break!

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