Practical A/B Testing Statistics: 5 Tips To Help You Get Reliable Data

Preview:

Citation preview

Your%Presenter

Michael%Aagaard

4 Senior%Conversion%Op:mizer%at%Unbounce%

4 Full4:me%CRO%for%the%lat%seven%years%

4 Interna:onal%speaker%

4 Founder%of%ContentVerve.com

Join%the%conversa:on

4%Include%the%hashtag%#thinkppc)in%your%TwiJer%tweets.%4%Or%use%the%webinar%ques:on%box%to%send%us%ques:ons.

“When can I stop my A/B Test?”

“Why run an A/B Test?”

To get a representative picture of how a variant would perform if implemented permanently “in the wild”.

To get a representative picture of how a variant would perform if implemented permanently “in the wild”.

Do Not Use 95% Significance Level as a Stopping Rule

1

After 1 day

+151.4% / significance 97%

655 visitors / 18 conversions

After 2 days

+98.4% / significance 95%

988 visitors / 23 conversions

After 1 week

+0.2% / significance 50%

3031 visitors / 58 conversions

After 2 weeks

+18.1% / significance 77%

5277 visitors / 78 conversions

After 4 weeks

+36.2% / significance 96%

Total sample: 9396 visitors / 122 conversions

What we have now: 9,396

What we need: 34,304 visitors in total

What we’re missing:24,908 visitors 73% of the required sample size.

http://www.evanmiller.org/ab-testing/sample-size.html

http://abtestguide.com/calc/

“Formulas don’t know whether they are being used properly, and they don’t warn you when your results are incorrect.”

- Deborah J. Rumsey, PhD

“Real accuracy depends on the quality of data as well as on the sample size.”

- Deborah J. Rumsey, PhD

Worth Getting Familiar With:

- Power Level - P-Value - Margin of Error - Confidence Interval - Null hypothesis / alternative hypothesis

Make Sure You Collect Enough Data to Yield Meaningful Insight

2

Full weeks Full business cycles

Weekly Business Cycle

Full weeks Full business cycles

Week One Week Two Week Three Week Four

Test duration: 2-4 weeks (2 or more business cycles)

Sample size: Pre-calculated sample size (users)

400+ conversions (goals)Significance: 95% or higher

Power: 80% P-Value: 0%

What I look for:

Be Careful With Averages - They Hide the Truth

3

Devices

Browsers

Channels

Country

Days of the week

Hours ofthe day

User types

Motivation

Campaigns

Age

Gender

Gender

BrowsersDevices

Browsers

Channels

Countries

Days of the week

Hours ofthe day

User types

Motivation

Campaigns

Age

Days of the month

Gender

Devices

Experiment

Integrate Test Data with Your Web Analytics Setup

And Get the Full Picture

Device?Channel?

Campaign?User Type?

Formulate a Clear Test Hypothesis

4

Why do we think we need to make a change?

What is it that we want to change?

What impact do we expect to see?

How will we measure this impact?

1. Because we saw [data/feedback]

2. We expect that [change] will cause [impact]

3. We’ll measure this using [data metric]

Because [exit surveys indicated that saving money is most important to our users.]

We expect that [tweaking our value prop to reflect this] will cause [more people to fill out our lead form.]

We’ll measure this using [form submission rate as our key metric.]

Because [exit surveys indicated that saving money is most important to our users.]

We expect that [tweaking our value prop to reflect this] will cause [more people to fill out our lead form.]

We’ll measure this using [form submission rate as our key metric.]

Because [exit surveys indicated that saving money is most important to our users.]

We expect that [tweaking our value prop to reflect this] will cause [more people to fill out our lead form.]

We’ll measure this using [form submission rate as our key metric.]

Because [exit surveys indicated that saving money is most important to our users.]

We expect that [tweaking our value prop to reflect this] will cause [more people to fill out our lead form.]

We’ll measure this using [form submission rate as our key metric.]

We expect to see reliable results in [four weeks.]

Learn Statistics!!!

5

http://amzn.to/1RFNBwA

Live%Q&A%Time

Have%more%questions?

Contact%Us%Directly

• Webinar%Feedback:%marketing@hanapinmarketing.com

____________________________________________

Thank'you'for'attending' our'webinar!'#thinkppc

Recommended