seo and ppc halo effect analysis

SEO and PPC Halo Effect Analysis

By Paul Morris

The debate of how paid search effects organic traffic and vice versa has raged within the search industry for years. I wrote an article on the very topic of seo/ ppc cannibalisation a few months ago however thought I would update my thoughts on the important issue of cannibalisation/ halo effect…

According to a cannibalisation study from Googlepaid search ads give a 89% incremental lift in site visitors – above and beyond traffic you would normally expect from your organic listings.

In a previous agency I worked for we managed Search for a large DIY company and proved that bidding on brand and brand+generic is worthwhile and generates incremental sales. i.e. agreeing with the Google study. Visitors would often use Organic Search links to navigate easily to a site’s homepage for research, before converting through Paid Search ads. This appeared to be due to the fact that paid links trigger conversion and seems like the better deal offering you more defined product benefits with stronger promotional messaging.

Don’t believe me? Don’t believe the fact that you should bid on brand and brand+generic when you have decent organic results? Good! Absolutely do not trust me and the philosophy of test and learn is the one you should follow as this generic piece of advice will not apply to all. Also the theory falls flat on its arse when the competitive landscape is not as strong in paid search or when your brand dominates the natural SERPS and you have little competition there either.

To conduct a fair halo effect test do the following:

  1.        Find a term you rank well for (1-3) in the natural SERPS
  2.        Add that keyword as an exact match negative in your PPC account(s)
  3.        Analyse the results over 7 days
  4.        Buy that same keyword for 7 days
  5.        Then compare the CTR, Natural clicks, conversion rates and ROI
  6.        Repeat until the results become statistically significant
  7.        Then taking things a step further vary point 4 above i.e. test lower/higher        PPC positions toascertain cost-benefit analysis

Note: Make sure you factor in environmental factors that could skew the results e.g. time of month, competitor activity, special offers that could skew CTR and conversion rates, etc and also factor in historic results e.g. the same week last year.

To go back a step; make sure you do not only use organic rankings to guide SEM strategy, as per the above example, and also use PPC to infer SEO strategy. By looking at your PPC results, you can see exactly how much traffic is available on keywords, and how well that traffic is likely to convert. Since you can only target a limited number of keywords for SEO, this can give you a clear guide of where to focus your efforts.

Also, PPC allows you to experiment with different advertising messages to find the ones that produce the best results (CTR and conversion rates). Use this data to improve your organic meta descriptions and see your CTR’s and/or conversion rates and/or LTV improve.

As an aside…
An extension of online halo effect testing is that of how offline + online halo effect tests = greater conversion coolness.
It’s interesting to see from studies such as that conducted by, Nuffield Health (end of the pdf) and Jupiter/ iProspect of how tying in your TV imagery with your website aids online conversion rate/ halo effect.

Own as much real estate to capture consumer interest across the SERPS as long as long it costs in from an ROI + brand perception perspective…

Play defence against your competition by driving greater coverage across the SERPS that in turn prevents leakage of traffic to competitor sites.

1 (SEO) + 1 (PPC) = >2 (SEM)