The document summarizes how a year of SEO split testing changed the author's understanding of how SEO works. Some of the key findings from the split tests included: (1) Title tests often changed traffic 5-15% but 56% were negative, (2) Structured data sometimes increased traffic over 10% but most changes had no effect, and (3) The same changes often had different or no effects on different sites, highlighting there are no universal "best practices". Split testing improved relationships by making arguments less necessary.

1. HOW A YEAR OF SEO
SPLIT TESTING CHANGED
HOW I THOUGHT SEO
WORKED
DOMINIC WOODMAN

4. Hmm that did
nothing
Crushing
failure
Ooh traffic went up

6. All those links I’m building.

8. Hmm that did
nothing
Crushing
failure
Ooh traffic went up

14. How does SEO testing
work & what do you need?

15. Getting started & learning
how to think about testing

16. More than you wanted to know
about titles and metas.

17. Testing resource
heavy investments

18. Structured data &
dangerous assumptions

19. Risky business...

20. How testing changes
relationships

21. Conclusions

22. How does SEO testing
work & what do you need?

23. SEO split testing is template basedHere’s our example website
Home
Animals
Cats Dogs Unicorns Badgers

24. CatsCats
We want to test two templates for our animals pages

25. Cats Dogs Unicorns Badgers
CRO test - Different users, see different templates on the same pages
1
2
Cats BadgersDogs Unicorns

26. Cats Dogs Unicorns Badgers
SEO test - different users see the same templates on different pages
1
2
Cats Dogs Unicorns Badgers
Cats Dogs Unicorns Badgers

27. Then we measure the change in traffic, e.g. 3% daily increase

29. LIABILITY

34. Rank
Search visibility

37. Total additional sessions

38. The fans show margin of error

39. The test is significant when the shaded area crosses 0

40. In this case it happened here:

44. There are two
graphs.

47. Control Variant

48. Black is organic traffic for the variant

49. Start date for the test

50. Take all the data to left and use that to make the model

51. The model of the variant is the blue line

52. We overlay them

53. Compare the model to the variant after the start date

54. In this case the black line is higher, it’s a positive test

55. A good model, fits with the variant before the start date

56. However this was my model. They don’t fit well.

57. How much traffic do you
need for SEO split testing?
Rule of thumb: you need roughly 1000 organic sessions a day to
the group of pages you’re testing.
#INBOUND2018 @dom_woodman

58. That model you
just saw, only had
~60 sessions a
day.

59. Getting started & learning
how to think about testing

60. 1

64. Some fluctuation but null.

66. 2

68. After

69. 10.8% decrease

71. 3

73. <img src="product1.jpg" alt="Home 6 Piece Towel Bale - Geo Grey /
Zest">

74. A model so perfectly null I thought I had forgotten to launch it

76. 4&5

77. Thought leader.
PHD in AI.
Unbearably smug.

79. Before:

80. After:

81. A stunning 27% drop.

83. A 20% drop.

84. Can’t write
titles to save
his life.

85. Get a testing framework
You need to be able to iterate and learn from tests. Having a
shared framework, will help with this.
#INBOUND2018 @dom_woodman

86. You don’t need the why
Knowing the why is great (find it if you can), but you don’t need
it to take action.
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87. More than you wanted to know
about titles and metas.

88. 6

89. 16

90. 1. Reviews
2. Safety Information

91. Before

92. After

93. 10% drop

94. 7

96. Before

97. After

98. 14.7% drop

99. Fast forward… more
tests happen.

100. Title tests usually change
traffic between ~5 - 15%
This stayed equivalent across site size and industry.
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101. 56% of all title tag
changes were negative
Around 37% were null and only 6% were actually positive. It’s really
hard to write a good title.
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102. Writing titles
is just really
really hard.

103. You can’t stop testing
titles.
Titles exist in the context of the rest of a SERP, when everyone
copies your good title format (and they will) you’ll have to mix it
up again.
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104. Title/meta effects typically
appear in 2-4 days.
It’s also easy to validate the changes have been picked up
because you can scrape it from the SERPS.
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105. Heavy investment
SEO changes

106. 8

107. We can render Javascript!

108. Javascript EnabledJavascript Disabled
Control

109. Javascript EnabledJavascript Disabled
Variant

110. 6.2% increase.

111. 5% increase

112. Visible content on the
initial page load matters
Although there is a lot subtlety to how Google renders JS, we
haven’t covered here.
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113. 9

115. No effect/negative effect

116. Increase of 3.1%

117. SEO content sometimes
helps… :(
Damn it.
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118. The same changes have
different effects on
different sites.
This is the big one. There really isn’t best practice.
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119. (Assuming it was topically similar). We’ve saved clients a lot of
money, by showing they could reduce content without an effect.
Reducing content on
non-article pages was
often null.
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120. Structured data &
dangerous assumptions

121. 10

124. Adding structured data to category pages

125. Increase of 11%

126. 11

127. Increase of 11%

128. $$$$$$ - 150K additional
sessions a month.
How did your last year go?

130. 12, 13,
14

132. Null.

133. Null.

134. Null.

135. The same changes have
different effects on
different sites.
This is the big one. There really isn’t best practice.
#INBOUND2018 @dom_woodman

136. The same changes have
different effects on
different sites.
This is the big one. There really isn’t best practice.

137. Structured data has an
effect outside of rich
snippets
Occasionally we got big 10-15% wins on important templates, it
varied wildly and was mostly null (never negative).
#INBOUND2018 @dom_woodman

138. Periodically re-challenge
your beliefs
I was lucky to test a successful site first. In a different order, I
might’ve given up on my hypothesis, before finding the right site.
#INBOUND2018 @dom_woodman

139. 15

141. Increase of 16%

142. 16

144. 5 star
much value
very marketer

146. 0.0% change. Again impressively null.

147. If you don’t have intent,
bells and whistles fail.
5 star rich snippets increased traffic by 16% on the right site with the
right intent. When the intent wasn’t there, they appeared, but did
nothing.
#INBOUND2018 @dom_woodman

148. Risky business...

150. 17

153. <time itemprop="dateModified" datetime="{{date}}">
Updated on: {{date}}
</time>

154. 8% increase

155. Freshness does matter.
But I wouldn’t recommend faking last modified dates...
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156. Agile testing can help
you take larger risks.
If you can measure and quickly roll out/roll back a test, you can try
things you might not normally feel comfortable doing.
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157. How testing changes
relationships

158. 18

159. BUSINESS
Synergy
Dynamic

163. Increase of 12%

164. Increase of 12%

165. Null. Go figure.

166. You don’t need to argue,
when you can test.
When you have solid testing framework and can build things quickly
and easily, testing is easier than arguing and removes arguments
from a relationship.
#INBOUND2018 @dom_woodman

169. Also null.

171. Happiness isn’t just up
and to the right
Instead the focus turns to other metrics like how many tests are we
running, how can we improve the testing process.
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172. A negative test you rolled
back is a bullet dodged
Negative tests feel like wasted time. Once you realise without testing
you probably would’ve rolled out, it feels a lot better.
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173. You’re about to be forced
out of silos.
You’re going to need to coordinate and work tightly with product and
QA teams if you’re not already.
#INBOUND2018 @dom_woodman

174. Conclusions

175. Hmm that did
nothing
Crushing
failure
Ooh traffic went up

176. The same changes have
different effects on
different sites.
Really can’t emphasize this one enough.
#INBOUND2018 @dom_woodman

177. Get a testing framework.
Most tests fail or are null.
Having a framework will help you move faster and find those wins.
#INBOUND2018 @dom_woodman

178. Testing will improve your
relationships.
You’ll have to spend less time arguing and it creates a culture of
curiosity.
#INBOUND2018 @dom_woodman

179. Periodically re-challenge
your beliefs
You probably have some beliefs about what works or doesn’t work
which are wrong from blind chance. Re-test them.
#INBOUND2018 @dom_woodman

180. Making changes to sections of pages
on templates
● Making SEO changes with tag
manager
● Cloud flare edge workers
● DistilledODN
General useful posts on testing
frameworks & velocity
● Hypothesis framework
● Running a weekly growth meeting
Do it yourself
How does split testing work?
● How does SEO split testing work?
Examples
● Pinterest - Demystifying SEO with
experiments
● Etsy - SEO title tag testing
Measuring SEO split tests
● Google’s original causal impact
paper
● A DIY tool for measuring SEO split
tests
● A walkthrough of the R Causal
Impact library

181. bit.ly/inbound-odn

182. bit.ly/inbound18-slides
@dom_woodman