T.-K Fan, C-H Chang/ Expert Systems with Applications 38(2011 )1777-1 tising(or content targeted advertising)(Anagnostopoulous et al. Rent Italian Luxury villa 2007: Broder, Fontoura, Josifovski, Riedel, 2007). Sponsored My World search, which delivers ads to users based on users' input query. can be used on sites with a search interface(e.g, search engines 25. off N Bus Passes Huge discounts on selected passes Contextual advertising, on the other hand is displayed on general web sites. These two techniques differ in that a sponsored search Ba: Bus.Hop on hop on analyzes only the user,s query key words, while content-based Very sad. The baby hasnt moved in two advertising parses the contents of a web page to decide which ads to show. However, the goals of each approach are consistent. hinking about The intent is to create a triple-win commercial platform. In other rs right now. Cheap Airline Tickets the Low words, an advertiser pay to purchase valuable adver Fares. Search 170+ Sites Save tisements, the ad agency system shares advertising profits with the Tokyos largest hostel web site owner(the publisher), and consumers can easily respond to ads to purchase products or services. Contextual advertising involves an interaction between four Relevant Ads players(Anagnostopoulos et al. 2007; Broder et al., 2007). The publisher, or the owner of a web site, usually provides interesting Fig. 1. Example of a blog page with correlation ads pages on which ads are shown. The publishers typically aim to en- gage a viewer, encouraging them to stay on their web page and, furthermore, attracting sponsors to place their ads on the page written with positive sentiment produces high click-through rates. The advertiser(the second player)supplies a series of ads to mar- Although a page-relevant topic is a way to capture visitors inter- ket or promote their products. The advertisers register certain est, there is no other way to determine their personal interests. characteristic keywords to describe their products or services However, since bloggers are constant visitors to their own blogs, The ad agency system( the third player) is a mediator between and their interests or intensions are well expressed in the weblogs, the advertisers and the publishers: that is, it is in charge of match- an ad agency could use those expressed intentions to place inter- ng ads to pages. The end user( the fourth player ) who browses For example, Fig. 1 shows a weblog with five ads related to trav web pages, might interact with the ads to engage in commercial eling placed on the right. Since the content of this page describes activities. In the pricing model of Cost Per Click( PC), also known reasons for cancelling a trip, these traveling ads are unlikely to as Pay Per Click(PPC)(Feng, Bhargava, Pennock, 2003), advertis- be clicked. Instead, what the blogger needs is medical information ers pay every time a user clicks on their ads. They do not actually pay for placing the ads, but instead they pay only when the ads are or information on doctors. The point here is that an ad agency sys- clicked. This approach allows advertisers to refine search keywords tem could assign relevant ads according to bloggers'own interests especially their immediate interest or intentions, for targeting ads, and gain information about their market. Generally, user clicks thus treating bloggers as the main visitors of their own blogs. To system. a number of studies have suggested that strong relevance this end, even if an ad is related to the content of a linking page, increases the number of ad clicks( Chatterjee et al, 2003; OneUp an ad agency should preferentially consider the immediate inter ests expressed on the page (i.e intentions for placing ads b, 2005; Wang et al, 2002). Hence in th we refer to as Blogger-Centric Contextual Advertising (BCCA), and is determined by the ad 's relevance score with respect to the page. which is based on latent interest detection to associate ads with For simplicity, we ignore the positional effect of ad placement and blog pages. Instead of the traditional placement of relevant ads, BCCA emphasizes that the ad agency s system should provide rel 2007: Lacerda et al, 2006: Ribeiro-Neto, 2005). evant ads that are related to ditterent levels of personal preferences content creation but do not host their own web sites, service pro in order to increase clicks To evaluate our proposed method, we viders sometimes play the role of ad agency. For example, many used a real-word collection comprised of ads and blog pages from blog service or portal service providers(such as Facebook, My- oogle AdSense and Google's Blog-Search Engine, respectively Our results show that the proposed approach, based on text mining pace, and Twitter)also have their own ad agency systems, which im to generate profits while providing their services. As we realize can effectively recognize the latent interests(e.g. intentions)in a that blog owners are constant visitors of their own web pages blog page or the personal interests of the blogger. In addition, we further investigated the effects of ad page matching using bringing personal ads to bloggers becomes promising. since blog d Click-Through-Rate( CTR)experiment, and our results suggest blogs. That is, the ad agency system of blog service providers could that our proposed method can effectively match relevant ads to a given blog page. gain an advantage by providing the right message in the right con text at the right time to bloggers. Note that this does not preclud background infor introduces our me Patio organized as follows: Section 2 provides on current online ac Section 3 argeting ads to visitors, but rather highlights a chance to target ology. The experime ts are pre- advertising to bloggers themselves. After all, advertising is about nted in Section 4. Section 5 outlines some we present conclusions and future directions in Section 6 rk. Finally. text to the right person(Adams, 2004: Kazienko Adamski, 2007). To explore the possibility of targeting advertising to bloggers, we conducted a simple survey of 62 bloggers about their experi- 2. Background ence in clicking ads and what types of advertisements on their blogs do they prefer. Among 50 participants who had experience There are two main categories of text-based advertising: spon- clicking ads on their blogs, 40 of them indicated that they tend sored search(or keyword targeted marketing) and contextual adver- to click ads which are related eir interests and immediate requirements, while the other 10 participants randomly trigger 2http://blogsearch.google.com ads without consideration of the correlation between ads and theirwritten with positive sentiment produces high click-through rates. Although a page-relevant topic is a way to capture visitors’ inter￾est, there is no other way to determine their personal interests. However, since bloggers are constant visitors to their own blogs, and their interests or intensions are well expressed in the weblogs, an ad agency could use those expressed intentions to place inter￾est-oriented ads. For example, Fig. 1 shows a weblog with five ads related to trav￾eling placed on the right. Since the content of this page describes reasons for cancelling a trip, these traveling ads are unlikely to be clicked. Instead, what the blogger needs is medical information or information on doctors. The point here is that an ad agency sys￾tem could assign relevant ads according to bloggers’ own interests, especially their immediate interest or intentions, for targeting ads, thus treating bloggers as the main visitors of their own blogs. To this end, even if an ad is related to the content of a linking page, an ad agency should preferentially consider the immediate inter￾ests expressed on the page (i.e., intentions) for placing ads. In this paper, we proposed an ad matching mechanism, which we refer to as Blogger-Centric Contextual Advertising (BCCA), and which is based on latent interest detection to associate ads with blog pages. Instead of the traditional placement of relevant ads, BCCA emphasizes that the ad agency’s system should provide rel￾evant ads that are related to different levels of personal preferences in order to increase clicks. To evaluate our proposed method, we used a real-word collection comprised of ads and blog pages from Google AdSense and Google’s Blog-Search Engine,2 respectively. Our results show that the proposed approach, based on text mining can effectively recognize the latent interests (e.g., intentions) in a blog page, or the personal interests of the blogger. In addition, we further investigated the effects of ad page matching using an ad Click-Through-Rate (CTR) experiment, and our results suggest that our proposed method can effectively match relevant ads to a given blog page. The rest of this paper is organized as follows: Section 2 provides background information on current online advertising. Section 3 introduces our methodology. The experimental results are pre￾sented in Section 4. Section 5 outlines some related work. Finally, we present conclusions and future directions in Section 6. 2. Background There are two main categories of text-based advertising: spon￾sored search (or keyword targeted marketing) and contextual adver￾tising (or content targeted advertising) (Anagnostopoulous et al., 2007; Broder, Fontoura, Josifovski, & Riedel, 2007). Sponsored search, which delivers ads to users based on users’ input query, can be used on sites with a search interface (e.g., search engines). Contextual advertising, on the other hand, is displayed on general web sites. These two techniques differ in that a sponsored search analyzes only the user’s query key words, while content-based advertising parses the contents of a web page to decide which ads to show. However, the goals of each approach are consistent. The intent is to create a triple-win commercial platform. In other words, an advertiser pays a low price to purchase valuable adver￾tisements, the ad agency system shares advertising profits with the web site owner (the publisher), and consumers can easily respond to ads to purchase products or services. Contextual advertising involves an interaction between four players (Anagnostopoulous et al., 2007; Broder et al., 2007). The publisher, or the owner of a web site, usually provides interesting pages on which ads are shown. The publishers typically aim to en￾gage a viewer, encouraging them to stay on their web page and, furthermore, attracting sponsors to place their ads on the page. The advertiser (the second player) supplies a series of ads to mar￾ket or promote their products. The advertisers register certain characteristic keywords to describe their products or services. The ad agency system (the third player) is a mediator between the advertisers and the publishers; that is, it is in charge of match￾ing ads to pages. The end user (the fourth player), who browses web pages, might interact with the ads to engage in commercial activities. In the pricing model of Cost Per Click (CPC), also known as Pay Per Click (PPC) (Feng, Bhargava, & Pennock, 2003), advertis￾ers pay every time a user clicks on their ads. They do not actually pay for placing the ads, but instead they pay only when the ads are clicked. This approach allows advertisers to refine search keywords and gain information about their market. Generally, user clicks generate profits for both web site publishers and the ad agency system. A number of studies have suggested that strong relevance increases the number of ad clicks (Chatterjee et al., 2003; OneUp￾Web, 2005; Wang et al., 2002). Hence, in this study, we similarly assume that the probability of a click for a given ad on a given page is determined by the ad’s relevance score with respect to the page. For simplicity, we ignore the positional effect of ad placement and pricing models, as in (Anagnostopoulous et al., 2007; Broder et al., 2007; Lacerda et al., 2006; Ribeiro-Neto, 2005). For many web 2.0 services, where publishers are responsible for content creation but do not host their own web sites, service pro￾viders sometimes play the role of ad agency. For example, many blog service or portal service providers (such as Facebook, My￾Space, and Twitter) also have their own ad agency systems, which aim to generate profits while providing their services. As we realize that blog owners are constant visitors of their own web pages, bringing personal ads to bloggers becomes promising, since blog￾gers’ profiles, opinions, short-term interests are expressed in their blogs. That is, the ad agency system of blog service providers could gain an advantage by providing the right message in the right con￾text at the right time to bloggers. Note that this does not preclude targeting ads to visitors, but rather highlights a chance to target advertising to bloggers themselves. After all, advertising is about delivering the right message at the right time and in the right con￾text to the right person (Adams, 2004; Kazienko & Adamski, 2007). To explore the possibility of targeting advertising to bloggers, we conducted a simple survey of 62 bloggers about their experi￾ence in clicking ads and what types of advertisements on their blogs do they prefer. Among 50 participants who had experience clicking ads on their blogs, 40 of them indicated that they tend to click ads which are related to their interests and immediate requirements, while the other 10 participants randomly trigger ads without consideration of the correlation between ads and their Fig. 1. Example of a blog page with correlation ads. 2 http://blogsearch.google.com. 1778 T.-K. Fan, C.-H. Chang / Expert Systems with Applications 38 (2011) 1777–1788