Incremental Clicks Impact Of Search Advertising David X. Chan, Yuan Yuan, Jim Koehler, Deepak Kumar Google Inc.

Abstract

results?” is not answered. Advertisers that pause their search advertising campaigns someIn this research we examine how the number of times cite concerns about how much of the traffic organic clicks change when search ads are present to the sites is truly incremental to clicks on natand when search ad campaigns are turned off. ural search results. We then develop a statistical model to estimate The incrementality is dependent on factors such the fraction of total clicks that can be attributed as the organic search result ranking and how to search advertising. A meta-analysis of several similar the paid and organic listings are to each hundred of these studies reveals that over 89% of other. By measuring the incremental click imthe ads clicks are incremental, in the sense that pact from search advertising, the advertiser is the visits to the advertiser’s site would not have able to make more informed decisions regarding occurred without the ad campaigns. their advertising spend.

1

Introduction

2

In recent years, as advertisers have sought to expand their media reach online, search advertising has become increasingly popular. US online advertising spend reached $26 billion in 2010, with search advertising making up 46% of the market. Total US online spend is projected to reached $42 billion by 2013 [1]. There are several advantages search advertising has over traditional media advertising. One involves access to direct metrics of impact, such as the number of clicks achieved. Another is search advertising allows advertisers to pay only when a user clicks on an ad. And yet another is that since the ads are triggered by search terms, they tend to be highly relevant to the user.

Methodology

In order to determine the incremental clicks related to search advertising, we quantify the impact pausing search ad spend has on total clicks. Indirect navigation to the advertiser site is not considered. Each study produces an estimate of the incremental clicks attributed to search advertising for an advertiser. To make comparison across multiple studies easier, we express the incremental clicks as a percentage of the change in paid clicks. This metric is labeled “Incremental Ad Clicks”, or “IAC” for short. IAC represents the percentage of paid clicks that are not made up for by organic clicks when ads are paused. Conversely, when the campaign is restarted, the IAC represents the fraction of paid clicks that are incremental. Since we do not assume a positive interaction between paid and organic search in our analysis, the IAC estimate is bounded at 100%. For example consider the following scenario:

However, measuring the number of ad clicks alone does not provide information on the incrementality of search advertising. That is, the question “how many of the clicks are incremental to clicks that would have occurred on natural search results in the absence of paid ad 1

2.2

Statistical Model

2

METHODOLOGY

(A) An advertiser spends $1,000 a month and the validation flags are included in this metareceives 400 organic and 300 paid clicks a analysis. month.

2.2

Statistical Model

(B) Subsequently, they cut their ad spend to $0 and find there are 500 organic clicks a month To determine incremental clicks from search adand 0 paid clicks a month. vertising, we need to know the paid and organic clicks at different spend levels over the same time Under (A), there are 200 incremental clicks, period. Since there can only be one spend level thereby giving an IAC of (700-500)/(300-0) = at any given time, we build a statistical model to predict the clicks in the post-period for any 66.7%. given level of spend. In the above example, we do not consider external factors which could also affect the organic We denote the high and low spend levels as SH clicks before and after the spend change. To con- and SL respectively, in the pre-period and posttrol for this, we employ the statistical model de- period. In the post-period when the spend level was low, we identify paid clicks as PL and toscribed below. tal clicks as TL . In the same post-period, if This estimate of 200 incremental click (IAC) dethe spend level were SH , and clicks PH and TH pends on factors leading to the ad spend drop were observed, the incremental clicks would be and the state of the account and competitive enT − TL . The IAC would then be vironment around the time of the spend change. H TH − TL Although the estimate of the IAC should always IAC = (1) PH − PL be considered in the context of the changes preceding the ad spend pause, a meta-analysis of all the Search Ad Pause studies provides insight However, since PH and TH can not be observed in the post-period, we substitute with modelinto the average IAC from search advertising. generated predictions PˆH and TˆH . To reduce the variance of the predicted IAC, we also substitute TL and PL with TˆL and PˆL , predicted by 2.1 Implementation Details the same statistical model. The estimated IAC The studies are implemented via an automated is pipeline which runs on a daily basis. The ˆ ˆ d = TH − TL IAC (2) pipeline first attempts to identify a change point. PˆH − PˆL In this case, the change point is the date on which the spend pause began. Also identified The statistical model for paid and organic clicks are a pre-period (a relatively stable period prior utilizes the search ad spend and organic impresto the spend change), and a post-period (a rela- sions as predictors. First, let tively stable period after the spend change). O − Organic clicks If the daily spend in the post-period declines by P − Paid clicks more than 95% from the daily spend in the preT − Total clicks (paid plus organic) period, the companies are labeled as “paused”. I − Organic search impression An analysis is run for each company identified S − Spend on paid search as having paused. The results are compared against validation checks on data integrity and We use the following Bayesian model: model quality. Validation checks are used to ensure confidence in the statistical model and the O = (I + α1 )(κ1 + (κ2 − κ1 )e−β1 S/I ), models predictions. Around 55% of all studies P = β0 (I + α2 )(1 − e−β2 S/I ), pass the validation flags. Only studies passing T = O + P. 2

Google Inc.

3

META-ANALYSIS RESULTS

3.1

IAC Statistics by Country and Vertical

The constraints for the parameters are

year. Figure 1 is a histogram plot of the IAC across all 446 studies. The average IAC across α1 , α2 > 0, β0 , β1 , β2 > 0, 0 < κ1 < κ2 < 1. all studies is 91%, with the median rate at 95%. Flat uninformative priors are used for the param- The average IAC weighted by the volume of paid eters. We also assume concavity for the marginal clicks in each study is 89%. More than 64% of the studies had an IAC value greater 90 with CPC, which is defined as ∂T ∂S . This assumption only a few studies showing a low IAC value. introduces an additional constraint r β0 β1 < . 1< β2 κ2 − κ1 50

40 Percent of Total

Gibbs sampling [2] and Slice sampling [3] are used to infer the posterior distribution of the model parameters, and to make predictions for the paid and organic click volumes. We ensure the model fits the observed data by setting stringent thresholds for adjusted r-squared, residual auto-correlation (Durbin-Watson statistic [4]) and Markov Chain Monte Carlo (MCMC) convergence (Gelman-Rubin statistic [5]). Additionally, we impose several minimum constraints on click volume and percentage of paid clicks among total clicks, to ensure there is adequate data for the model.

30

20

10

0 20

40 60 Incremental Ad Clicks

80

100

Figure 1: Histogram of Incremental Ad Clicks

3

Meta-Analysis Results

The meta-analysis is based on 446 valid studies conducted between October, 2010 to March, 2011. Table 1 summarizes the study count for four countries by the month the study was produced. Date 10/2010 11/2010 12/2010 01/2011 02/2011 03/2011 Total

DE 2 6 14 22 9 5 58

FR 3 2 3 19 7 2 36

GB 4 0 1 16 8 5 34

US 11 9 63 110 65 60 318

A low value for IAC may occur when the paid and organic results are both similar and in close proximity to each other on the search results page. This increases the likelihood of a user clicking on an organic result as opposed to a paid result. Close proximity occurs when the ranking of the organic result is high, placing it near the paid results. Organic results triggered by branded search terms tend to have a higher ranking on average and this may lead to a low IAC value. However, a low IAC value is not necessarily a deterrent to investing in search advertising. Section 4 discusses in more detail when it would be worthwhile to make such an investment.

3.1 Table 1: Count Of Search Ad Pause Studies In January 2011, we saw an increase in the number of companies that paused their search advertising. This increase may correspond to advertisers revisiting their ad spend budgets for the Google Inc.

IAC Statistics by Country and Vertical

We now consider IAC statistics by country, industry vertical and daily spend level. Table 2 includes both the mean and median IAC for each country. 3

4

Country Germany (DE) France (FR) United Kingdom (GB) United States (US)

N 58 36 34 318

Mean 87% 88% 90% 90%

Sd 16% 10% 14% 14%

WHEN IS SEARCH ADVERTISING WORTHWHILE?

Median 94% 88% 96% 95%

Table 4 summarizes the IAC by the pre-period daily spend level. The studies were split into four quartiles according to their pre-period daily spend level. Spend level 1st Quartile 2nd Quartile 3rd Quartile 4th Quartile

Table 2: IAC Statistics by Country Table 3 summarize the IAC statistics by industry vertical. We have omitted industry verticals with less than 20 studies from the table and boxplot. Industry Vertical Classifieds & Local Retail Finance Healthcare Technology Consumer Packaged Goods Automotive Business & Industrial Markets Food & Beverages

N 62 59 41 38 28 26

Mean 94% 87% 88% 93% 90% 88%

Sd 9% 18% 16% 11% 14% 14%

Median 97% 94% 95% 98% 96% 94%

N 112 111 111 112

Mean 88% 92% 88% 88%

Sd 15% 10% 15% 15%

Median 94% 96% 95% 94%

Table 4: IAC Statistics by Spend Level

4

When Is Search Advertising Worthwhile?

Percent of Total

As noted earlier, a low IAC value does not necessarily suggest a pause in search advertising is in order. In fact, for many advertisers with a low 24 88% 13% 94% IAC, it is still profitable to invest in search ad24 93% 8% 96% vertising. To evaluate the economic benefits of 24 89% 15% 95% search advertising, an advertiser must run a calculation incorporating their individual IAC, conTable 3: IAC Statistics by Industry Vertical version rates, and conversion revenue. The below equation can help determine whether search Figure 2 is a histogram plot of the daily search advertising is worthwhile on a case by case basis. ad spend in the pre-period on a log10 scale. For Let v be the value of a paid click to the adverconfidentiality reasons, the numbers on the xtiser, c be the cost of a paid click and rv be the axes have not been included. value of an organic click, where r is a multiplier indicating the relative value of an organic click ˆ H and OˆL be the predicted to a paid click. Let O organic clicks at the high and low level of spend, 20 respectively. If the profit from paid clicks plus organic clicks exceeds the value of the organic clicks alone, it is profitable to buy search ads. 15 ˆ H > (v − c)PˆL + rv O ˆL (v − c)PˆH + rv O

Re-arranging this expression gives the following inequality v−c d > r(1 − IAC) 5 v d is defined in (2). The left-hand side where IAC is the profit margin on clicks. The right-hand 0 side is the relative value of organic clicks times (log10) Pre Period Ad Spend the displacement percentage which is one minus Figure 2: Histogram plot of daily pre-period the IAC. Advertisers are more likely to advertise search ad spend when 4

10

Google Inc.

REFERENCES

1. the profit margin on clicks is high,

REFERENCES

Acknowledgments

We would like to thank Hal Varian and Tony Fagan for their encouragement and support. Adam Ghobarah and Jen Silverstein, for their insightful 3. the relative value (r) of organic clicks is low. discussion and constructive feedback. Ori Gershony, Andrei Pascovici, Shri Brode and Anu Rawal, who helped build the production system for Search Ad Pause studies. Murray Stokely and Steve Scott for their help with implement5 Concluding Remarks ing the Bayesian estimation method and Lizzy We have examined those accounts which have ex- Van Alstine and Ann Farmer for their editorial hibited a spend pause and for which our models contributions. Thank you also to the many othproduce valid results. The meta-analysis is not ers at Google who made this paper possible. representative of all the possible factors which could drive ad spend decline. However, given the References large volume of studies produced, across multiple countries and industry verticals, our analy[1] Grabstats Internet Advertising / Onsis does provide a reasonable cross section of exline Advertising Revenue 2000 - 2008 pected IAC. It is also reasonable to assume that http://www.grabstats.com/statmain.asp?StatID=1 seasonality could play a part in the IAC that we estimate. As of yet, we have not accumulated [2] J. S. Liu. Monte Carlo Strategies in Scienough studies over a long enough time period entific Computing. New York: Springerto determine the impact of seasonality on IAC. Verlag, 2001. 2. the replacement factor is low, and

A more rigorous approach to determining IAC would be to conduct a randomized experiment. A test group would be exposed to the pull back in paid search ads while search spend would be held constant in a control group. A comparison of the paid and organic click volumes in the two groups would then yield an IAC estimate. However, many advertisers are adverse to conducting such experiments due to the setup costs involved and the potential revenue impact from having a hold-out group. In the case of spend pauses, advertisers presumably believe the benefit of pausing their spend outweighs lost revenue.

[3] R. M. Neal. Slice Sampling. Statistics, 31(3):705-767, 2003.

Annals of

[4] J. Durbin and G. S. Watson. Testing for Serial Correlation in Least Squares Regression, I. Biometrika, 37(3-4):409-428, 1950. [5] A. Gelman and D. B. Rubin. Inference from iterative simulation using multiple sequences. Statistical Science, 7(4):457-511, 1992.

Ultimately, advertisers are interested in how much income can be attributed to their search advertising campaigns. Our analysis does not include an estimate for incremental conversions. Other factors such as the ranking of the organic search result or the strength of brand awareness of the search term could influence the IAC estimate. Being able to track these factors for each study will allow us to better understand their influence on the IAC estimate. Google Inc.

5

Incremental Clicks Impact Of Search Advertising - Research at Google

Google Inc. Abstract. In this research ... search advertising has over traditional media ad- vertising. ... across multiple studies easier, we express the in- cremental ...

199KB Sizes 4 Downloads 502 Views

Recommend Documents

Incremental Clicks Impact Of Mobile Search ... - Research at Google
[2]. This paper continues this line of research by focusing exclusively on the .... Figure 2: Boxplot of Incremental Ad Clicks by ... ad-effectiveness-using-geo.html.

Impact Of Ranking Of Organic Search Results ... - Research at Google
Mar 19, 2012 - average, 50% of the ad clicks that occur with a top rank organic result are ... In effect, they ... Below is an illustration of a search results page.

Incremental Crawling - Research at Google
Part of the success of the World Wide Web arises from its lack of central control, because ... typically handled by creating a central repository of web pages that is ...

The Incremental Reach and Cost Efficiency of ... - Research at Google
ads and whether a cross-media campaign would be more cost-efficient for reaching their target ... media campaign would have delivered at least the reach of the TV campaign. ...... [3] US TV Ad Spending(2009-2015), eMarketer, March 2011.

Incorporating Clicks, Attention and Satisfaction ... - Research at Google
the model predict click vs. satisfaction events? RQ2 Does an offline ... ing a SERP item [26] and even the satisfaction reported by the user [27], based on mouse ...

Data Enrichment for Incremental Reach Estimation - Research at Google
small data set and B for big data set. Our methods for improvement are based on the decomposition θ = Pr(Z = 1) Pr(Y = 0 | Z = 1). Under the IDA, we can use the ...

Large-scale Incremental Processing Using ... - Research at Google
language (currently C++) and mix calls to the Percola- tor API with .... 23 return true;. 24. } 25. } 26 // Prewrite tries to lock cell w, returning false in case of conflict. 27 ..... set of the servers in a Google data center. .... per hour. At thi

Google Search by Voice - Research at Google
May 2, 2011 - 1.5. 6.2. 64. 1.8. 4.6. 256. 3.0. 4.6. CompressedArray. 8. 2.3. 5.0. 64. 5.6. 3.2. 256 16.4. 3.1 .... app phones (Android, iPhone) do high quality.

Google Search by Voice - Research at Google
Feb 3, 2012 - 02/03/2012 Ciprian Chelba et al., Voice Search Language Modeling – p. 1 ..... app phones (Android, iPhone) do high quality speech capture.

On the Impact of Kernel Approximation on ... - Research at Google
termine the degree of approximation that can be tolerated in the estimation of the kernel matrix. Our analysis is general and applies to arbitrary approximations of ...

Query-Free News Search - Research at Google
Keywords. Web information retrieval, query-free search ..... algorithm would be able to achieve 100% relative recall. ..... Domain-specific keyphrase extraction. In.

Google Search by Voice - Research at Google
Kim et al., “Recent advances in broadcast news transcription,” in IEEE. Workshop on Automatic ... M-phones (including back-off) in an N-best list .... Technology.

Voice Search for Development - Research at Google
26-30 September 2010, Makuhari, Chiba, Japan. INTERSPEECH ... phone calls are famously inexpensive, but this is not true in most developing countries.).

The Impact of Memory Subsystem Resource ... - Research at Google
sources on five Google datacenter applications: a web search engine, bigtable ... havior and discover that the best mapping for a given ap- plication changes ... Machines have multiple sockets hosting proces- sors with multiple ... 9 10. 3 MB L2. 11.

Do Viewers Care? Understanding the impact of ... - Research at Google
TV advertising, and that these reactions can then be used to rank creatives by their apparent relevance to the viewing audience. 1 Why viewers tune away.

Perceived Frequency of Advertising Practices - Research at Google
Jul 24, 2015 - tice was beneficial or harmful, their technical understand- ing of that ... pant demographics, such as age and education level, as well as asking ..... 171 q. 114 q. 94 q. 379 q. 1241 q. 519 q. 1233 q. 1105 q. 470 q. 212 q. 550 q.

On the Difficulty of Nearest Neighbor Search - Research at Google
plexity to find the nearest neighbor (with a high prob- ability)? These questions .... σ is usually very small for high dimensional data, e.g., much smaller than 0.1).

Topical Clustering of Search Results - Research at Google
Feb 12, 2012 - that the last theme is easily identifiable even though the last three ..... It goes without saying that we have to add the cost of annotating the short ...

Retroactive Answering of Search Queries - Research at Google
May 23, 2006 - [email protected]. ABSTRACT. Major search engines currently use the history of a user's actions ... H.3.4 [Information Systems]: Information Storage and ...... users' standing interests and needs, and existing technology intended to ...

On the Predictability of Search Trends - Research at Google
Aug 17, 2009 - various business decisions such as budget planning, marketing ..... the major characteristics of the underlying time series are maintained.

Search Advertising
May 27, 2011 - the Eiffel Tower wants to launch an advertising campaign. ... of advertising: the social costs due to imperfect information (bad matches and high ... producing an homogenous good, and in which consumers incur a .... Page 10 ...... (200

Search Advertising
May 27, 2011 - advertising through national TV or newspapers is probably too expensive. .... contributions which study internet search engines and two-sided markets. ...... Service Providers,” R ND Journal of Economics, 34(2), 309–28.