The impact of metadata implementation on webpage visibility in search engine results (Part II) q

Transcription

1 Information Processing and Management 41 (2005) The imact of metadata imlementation on webage visibility in search engine results (Part II) q Jin Zhang *, Alexandra Dimitroff School of Information Studies, University of Wisconsin Milwaukee, Milwaukee, WI 53211, USA Received 12 August 2003; acceted 1 December 2003 Available online 21 January 2004 Abstract This aer discusses the imact of metadata imlementation in a webage on its visibility erformance in a search engine results list. Influential internal and external factors of metadata imlementation were identified. How these factors affect webage visibility in a search engine results list was examined in an exerimental study. Findings suggest that metadata is a good mechanism to imrove webage visibility, the metadata subject field lays a more imortant role than any other metadata field and keywords extracted from the webage itself, articularly title or full-text, are most effective. To maximize the effects, these keywords should come from both title and full-text. Ó 2003 Elsevier Ltd. All rights reserved. Keywords: Search engine otimization; Webage lacement; Webage visibility; Metadata 1. Introduction Internet information is characterized by the instability of its contents, decentralization of locations, multilicity of forms, diversity of user grous, and dynamics of the environment. The amount of information on the internet continues its tremendous growth, and the size and number of sources aear to be growing at an exonential rate (Kobayashi & Takeda, 2000). At least one study shows that users have become more diverse and that they send more and more time on the internet (GVUÕs 9th WWW User Survey: Web and Internet Use Summary, 2003). Findings indicate that 23% of webages change daily, in the.com domain, more than 40% webages change q The research was suorted by an IMLS National Leadershi Grant (#NR ). * Corresonding author. addresses: [email protected] (J. Zhang), [email protected] (A. Dimitroff) /$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved. doi: /j.im

2 692 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) daily, and the half-life of the ages is about 10 days (in 10 days half of these ages have gone) (Arasu, Cho, Garcia-Molina, Paecke, & Raghavan, 2001). These features make the roblems of web resource discovery and descrition more comlex and sohisticated. It is aarent that it has been an increasingly comlex challenge for internet searchers to find relevant information in the digital universe through the use of internet search engines. Not surrisingly, information science researchers as well as a growing grou of information entrereneurs have begun evaluating the erformance of various search engines in terms of their success in assisting searchers with relevant information retrieval. Reviews of the literature about search engine erformance and usersõ search behavior, however, focus on one viewoint: that of the user. (Bilal & Kirby, 2002; Leighton, 1997; Lowley, 2000; Pu, Chuang, & Yang, 2002; Schwartz, 1998; Yu & Roh, 2002). This addresses the needs of only half of the internet user community. The internet has created an unaralleled oortunity for users to access knowledge roducts on a just-in-time and on-demand aroach (H am al ainen, Whinston, & Vishik, 1996). More and more eole and organizations now ublish on the internet. Web ublishers are a growing oulation of internet users. Because most internet users emloy search engines as a rimary tool to ta internet resources (Haltley, 2002), every internet web ublisher wants good webage visibility in search engine results lists so as to increase accessibility of their webages. Web site visibility and accessibility are extremely imortant when web ublishers are targeting the tyical internet user, i.e., one who usually does not know a web address before searching. Unfortunately, many web sites have oor visibility in search engine rankings or may not be listed at all due to various reasons. Note, too, that it is a tremendous challenge for internet ublishers to insure that their web sites aear at the to of a search engine return list, maximizing visibility. It is widely recognized that many variables contribute to a successful and highly visible web site in a search engine results list. A search engine crawls a webage on the internet, extracts keywords based on its content, and indexes it in its database before that webage becomes available for a search query (Arasu et al., 2001). A well-designed, content-rich, and easily navigated site is very imortant. However, if a web site is not crawled and indexed by search engines or it is crawled and indexed but not well otimized, only a limited number of internet searchers will likely access it and all of the effort made with regard to webage content would be wasted. In other words, simly osting a webage on a ublic domain or submitting it to hundreds of search engines does not necessarily lead to a successful resence of that web site on internet search engine results lists. Automatic indexing based on a webageõs full-text has been widely used by internet search engines. However, automatic indexing techniques are most effective in a relatively small collection within a given domain. As the scoe of their coverage exands, indexes succumb to roblems of large retrieval sets and roblems of cross discilinary semantic drift (Weibel, 1995). It is obvious that automatic indexing techniques are not enough to handle internet information because the internet is huge, dynamic, and diverse. These features call for a simle, comatible, and convenient internet information descrition standard to assist and facilitate automatic indexing internet information effective and efficiently. Since creators of webages are usually not exerts in information retrieval, in fact many are content secialists with only the technical skills needed to transfer content to this medium, an information retrieval standard for imroving accessibility should be designed for use by web designers and ublishers with varying backgrounds. The introduction of metadata may become such a standard. Metadata attemts to facilitate understanding, identifying, describing, utilizing, and retrieving internet information sources and their contents.

3 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Metadata is broadly defined as data about data. In rincile, metadata rovides an effective mechanism for describing and locating data that is relevant to a articular user (Burnett, Ng, & Park, 1999). The standard enhances cross-discilinary discovery, offers a concetual framework that suorts the modular develoment of auxiliary metadata comonents, is used as a global standard for resource discovery, and defines a common ground of rinciles, rocedures, core semantics, and a framework to suort interoerable metadata (Weibel, 2000). Metadata develoment requires substantial cooeration and collaboration across different otential user grous. Organization of metadata information in hysical form is designed in a more flexible and structural electronic form; it fits for multile logical organization of information; and it facilitates internet information identification and extraction (Smith, 1996). Metadata research has become a hot research toic, ranging from its alication in digital libraries (Hill, Janee, Dolin, Frew, & Larsgaard, 1999), and digital museums (Zeng, 1999), to its imact on information retrieval (Cortez, 1999). Including metadata in a webage is not mandatory: it is voluntary and ad hoc in its imlementation. Internet ublishers can select metadata elements and embed them directly in their webages at will. Search engines use the metadata sulied in webages to extract keywords and other related information for webages and use them as index terms in their databases. Over the ast several years, more and more web ublishers have realized the imortance of metadata and have added it to their webages. According to one study, the number of web sites that contain one or more metadata tags aroaches 70%, keyword metadata 17% and descrition metadata 15% (OÕNeill, Lavoie, & McClain, 2001). However, there is a big difference between creating metadata tags and otimizing your site for high ranking and visibility in search engine results lists. In other words, adding metadata to a webage is one thing and getting a satisfactory ranking osition is another. It is not enough to simly add META tags and to submit your web site to search engine indexes and directories. The rocess of creating metadata can involve both subjective and objective inut. Some metadata is clearly objective: assertions of fact about authorshi, date of creation, version, and other attributes that are generally able to be determined in an objective way. Other metadata may be subjective because such elements are subject to differing oints of view (assignment of keywords, summarization of content in an abstract) (Duval, Hodgins, & Sutton, 2002). Successful use of metadata to communicate meaning of information relies on usersõ understanding or awareness of otherõs interretation of the domain and how this interretation is reflected in the metadata statement (Brasethvik, 1998). The findings (Sokvitne, 2003) demonstrate that there are misuses and inconsistencies in metadata element alication in a webage (title, creator/ublisher, and subject). Furthermore, metadata users lack a clear icture of how metadata elements in a webage behave with resect to visibility in search engine results lists. In other words, the effect of metadata alication for imroving information discovery cannot be maximized until eole understand the domain clearly, interret it in the context of metadata correctly, and comrehend the behavior of metadata elements fully. Search engine otimization has become a very comlex, sohisticated ractice that requires constant research, ractice, and reevaluation to be effective. A growing industry has blossomed that offers advice (for a fee in most cases) on maximizing webage lacement (for examle, Search Engine Advice (htt:// Search Engine Otimization Promotion Tools (htt:// Want to drive more traffic to your web site? (htt://

4 694 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Search Engine Ranking (htt:// Strategies for High Search Engine Rankings (htt:// and Search Engine Positioning mid Otimization; How easy are you to find? (htt:// This advice about which techniques will rovide otimal ranking results is hinted at on these organizationsõ web sites themselves but none of those offering advice describe the emirical research on which their recommendations should be based. While a common theme among these advice-givers is location, location, location the secific advice is fairly generic and based on conventional wisdom, How search engines rank Webages (htt:// webmasters/rank.html). Little research has been done on this toic (Schwartz, 1998) Objectives The objectives of this research were threefold: (1) to identify both internal and external factors of metadata elements within a webage that imact ranking in search engine results lists, (2) to comare the imact of those design factors in a webage on the webage visibility in a search engine, and (3) to develo a ractical metadata imlementation strategy or aroach to imrove ranking of a webage from an internet search engine. Notice that all factors secified in this study can be controlled and managed by webage develoers and designers. The significance of this research is that the findings will hel web ublishers increase traffic to their web sites by alying metadata element design features that will otimize ranking in search engine results lists Research question and hyotheses This study examined various metadata design factors and their relationshi to search engine results list lacement. The rimary research question was: How can the ranking of a web site in a search engineõs results list be imroved after metadata is imlemented? That is, how can the visibility of a webage in a search engineõs results list be otimized if metadata is embedded in a webage? Visibility is defined as the ranking osition in a search engine results list. The nearer to the to of a search results list, the better its visibility, and vice versa. Based on the rimary research question, five hyotheses were tested. They are: (1) Hyothesis 1(H1) There is no difference in search result visibility erformance between webages with metadata element imlementation and those without metadata element imlementation. (2) Hyothesis 2(H2) There is no difference in search result visibility erformance among web ages with different numbers of metadata element combinations in a webage. (3) Hyothesis 3(H3) There is no difference in search result visibility erformance among web ages with metadata title, webages with metadata subject, and web ages with metadata descrition. (4) Hyothesis 4(H4) There is no difference in search result visibility erformance among web ages with different metadata element combinations of metadata title, metadata subject, and metadata descrition as well.

5 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) (5) Hyothesis 5(H5) Keywords in metadata extracted from webage title, webage full-text, or both make no difference in search result visibility erformance in a search engine results list. At a broader level, if all webages were classified into two distinct categories webages with metadata and webages without metadata web ublishers would definitely ask which is better in terms of search result visibility erformance. Hyothesis HI attemts to answer this question. Hyotheses H2 H5 address the imact of metadata elements on webage visibility. These hyotheses try to answer how the metadata elements affect webage visibility. H5 focuses on imact of keyword source of metadata elements on the webage visibility while H2, H3, and H4 concentrate on imact of each individual metadata field (title, subject, or descrition), and their different combinations on search visibility. Hyotheses H2 and H4 look similar but in fact are subtly different. H2 treats metadata element combinations, in which the number of metadata combinations is the same, as the same grou regardless of combination contents. H4, however, breaks them down into several grous and treats them differently in the statistical test. That is why H2 has only three different comarison grous while H4 has seven different comarison grous. H2 and H4 are comlementary to each other. H5 addresses the external factors of metadata while H2, H3, and H4 address internal factors of metadata. 2. Exerimental design 2.1. Creation of test webages and osting of these webages Webage content characteristics analysis In this study, we investigated internal and external factors that might imact webage visibility in a search engine results. The internal factors refer to location and frequency of a keyword in a metadata element. In this case, the keyword which is used in a metadata element is selected and defined. That is, the selected keyword(s) reflect subject content of the webages. The external factor refers to where the keyword(s) used in a metadata element comes from in a webage. A keyword can be extracted from a webage title, webage full-text, or from outside the webage. It emhasizes the source of the keyword. Toward this aim, the keyword location and its frequency in webage title or webage full-text, in conjunction with the keyword location and its frequency in a selected metadata element, are considered as the web content characteristics in testing webage design. Both the internal and external factors are categorized and listed as follows: (a) Metadata: As is conventionally understood, metadata can be defined literally as data about data, but the term is normally understood to mean structured data about digital (and nondigital) resources that can be used to hel suort a wide range of oerations. Observe that Title, Creator, Subject, Descrition, Publisher, Contributor, Date, Tye, Format, Identifier, Source, Language, Relation, Coverage, and Rights are defined as basic metadata elements (in the Dublin Metadata Set). Among them, Title, Subject, and Descrition were singled out for this exeriment because the content of the three elements are directly related to the subject content of a webage

6 696 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) and keywords in these fields have the most otential to be crawled by search engines and further indexed as indexing terms in their databases. (b) Keyword dulication: We hyothesize that keyword frequency within a webage or a metadata field would make a significant contribution to its visibility in a search engine results list. Dulication of a keyword can haen in a title, a full-text, or a selected metadata element. In this study, the maximum keyword frequencies for title, full-text, metadata title field, metadata subject field, and metadata descrition field are set to 4, 5, 4, 4, and 4 resectively (see Table 1). (c) Combination of these factors: Various meaningful combinations of metadata title field, metadata subject field, and metadata descrition field were taken into consideration. This offered the oortunity to observe the imact of factor combinations on return result of a search engine. The considered factor combinations are dislayed in Table 2. (d) Keyword osition: We believe that the osition of a keyword within a webage lays an imortant role in terms of its return results list in a search engine. Following this line, a keyword in a title and a keyword in full-text were treated searately. In Tables 1 and 2, each row reresents a designed webage and each column reresents one of the identified content characteristics. Tables 1 and 2 give an overview icture of the identified webage content characteristics and test webages. They should hel readers understand how the exerimental webages were generated and to see how the characteristics are distributed among the test webages. These tables would be very helful in describing the data analysis. Each derived webage is assigned a unique identification code that would be used in later tables and data analysis (see left column of each table). The aearance status column in both tables refers to whether or not the test webage was retrieved using one of the search engines Creation of testing webages The original webage was modified based on content characteristics and more than 40 test webages were derived for the study. Each derived webage reresents one of the webage content characteristics in Tables 1 or 2. The content of the original webage was slightly revised and modified when some derived webages were generated. These changes included discarding or adding some keywords to title, full-text, or other defined metadata fields, changing term forms, and inserting the investigator names into each of the test webages. After subject analysis, the keyword acuuncture was identified as the indexing term for the derived webages. Each derived webage was given a secial HTML file name from which the investigators could easily trace its content characteristics during observation and data collection. It also facilitated later data analysis. Table 1 shows the distribution of the rimary keyword acuuncture in the derived webages. The number in the sub-columns reresents the frequency of acuuncture in the webages. For instance, acuuncture aears one time, two times, three times, four times, and five times in a test ageõs full-text (see Table 1). The combination imact of different webage content characteristics is illustrated in Table 2. The derived webages were osted in an internet ublic domain so that search engines and users would have free access to them. We then identified search engines with webage htt submission features. All search engines that charged a fee for submission were eliminated from the

7 Table 1 Keyword dulication Webage Title Full-text Metadata title field Metadata subject field W_P_1 W_P_2 W_P_3 W_P_4 W_P_5 W_P_6 W_P_7 W_P_8 W_P_9 W_P_10 W_P_11 W_P_12 W_P_13 W_P_14 W_P_15 W_P_16 W_P_17 W_P_18 W_P_19 W_P_20 W_P_21 Metadata descrition field Aearance status J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005)

8 698 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Table 2 Combination of factors Webage Title Full-text Metadata title Metadata subject Metadata descrition field field field W_P_22 W_P_23 W_P_24 W_P_25 W_P_26 W_P_27 W_P_28 W_P_29 W_P_30 W_P_31 W_P_32 W_P_33 W_P_34 W_P_35 W_P_36 W_P_37 W_P_38 W_P_39 W_P_40 W_P_41 W_P_42 W_P_43 W_P_44 W_P_45 W_P_46 Aearance status identified search engine list. Finally, the web addresses of the derived testing webages were submitted to each of the free submission search engines. Based on the content of the original webage, search strategies for the study were formulated. The search queries were used to search all the submitted search engines on a weekly basis. Webage file name, osition in a results list, search engine name and other related information were recorded if a webage was hit in a search engine. The exeriment ended after 21 weeks of data observation. 3. Data analysis In this study, a total of 46 webages were osted and submitted to 19 search engines. The test webages ultimately showed u in eight search engines. The reasons for non-aearance in some of the search engines varied. Some search engines merged with others, some were no longer available after test webage submission, some of the search engine servers did not work roerly, and some simly never indexed the submitted test webages. Among the 46 webages, only 28 webages finally aeared in results lists of one or more search engine. The remaining 18 web-

9 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Google EntireWeb Yahoo AltaVista AllWeb Netscae Inforsace/Fast Lycos ages never resented in any search engine results list. The number of test webages that aeared varied in different search engines, ranging from 5 to 11. See Fig. 1 for the average webage resentation numbers for the search engines. In Fig. 1 the X -axis is defined as the average number of retrieved test webages in a search engine and Y -axis is search engine Test webage aearance analysis Fig. 1. Average number of retrieved test webages for search engines. After checking to see which test webages were retrieved (identified in the far right columns of Tables 1 and 2, where a bullet in the column means the corresonding test webage aeared in at least one of the search engine results), we found 18 webages never showed u in the exerimental study. In Table 1, W_P_10, W_P_11, W_P_12, W_P_13, W_P_14, W_P_15, W_P_16, W_P_17, W_P_18, W_P_19, and W_P_21 did not aear in any search engineõs results list. W_P_20, which falls within the Metadata descrition field category, aeared just once in the Google search engine. It is interesting that all non-retrieved test webages were distributed in the categories Metadata title field, Metadata subject field, and Metadata descrition field and, imortantly, that the keywords used in the metadata elements did not come from either title or full-text of the test webages. This suggests that if a keyword which does not aear in the title and fulltext of a webage, is used as a keyword in metadata fields (subject, title, and descrition), the ossibility for it being crawled, indexed, and included by a search engine is very slim. Note that there is an excetion: one test webage (W_P_20) meeting these conditions did aear in the return list of a search engine but the frequency (only one time) is very very low comared to other resented webages. The situation in Table 2 is more comlicated. Pages W_P_25, W_P_29, W_P_30, W_P_31, W_P_39, W_P_41, and W_P_45 were never retrieved. Notice that several of them followed the same attern identified in Table 1: These webages (W_P_29, W_P_30, W_P_31, and W_P_41) were not in either the title or full-text categories but in the metadata fields (metadata title field, metadata subject field, and metadata descrition field) were simly excluded from any search result. This further corroborates and confirms the revious conclusion that keywords only in metadata fields result in low likelihood of retrieval. The last three un-retrieved test webages (two titles and one full-text) do not fit this attern. They were exected to show u but they did not resent in any search engine.

10 700 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) % 40.00% 30.00% 20.00% 10.00% 0.00% AllWeb Netscae Inforsace/Fast Yahoo AltaVista Lycos Google EntireWeb Fig. 2. Aearance rates for search engines. In Fig. 2, the aearance rates of valid osted webages for the eight search engines are listed, where the X -axis is the aearance rate and Y -axis is search engine. The aearance rate is defined as the ratio of the total number of retrieved unique osted webages in a search engine during the exerimental study to the number of all valid unique osted webages. The valid osted webages refer to all defined webages in Tables 1 and 2. The aearance rate can be used to measure indexing coverage of a search engine. A high aearance rate means a better indexing coverage for a search engine. Search engines Google and Alta Vista achieved the best and worst erformance in terms of search engine database indexing coverage, resectively. Note that the aearance rates for all search engines are relatively low. This can be exlained by the fact that many osted webages emloyed the keywords that did not aear in both title and full-text as their metadata keywords while these webages were not exected to show u in any search engine results list. The design and inclusion of these webages was for confirming this claim. Table 3 shows the distribution of test webage aearances in the search engines. This table will give readers a better icture of how the osted webages aeared in the search engines. It is clear that no search engine included all osted test webages. Fig. 3 shows the frequency distribution of all osted test webages across the eight search engines. In Fig. 3 the X -axis is the number of search engines where the same webages showed u and the Y -axis is the corresonding webage frequency. SE stands for search engine. For instance, the frequency of different osted webages that showed u in none of the eight search engines is 18 while the frequency of different osted webages that aeared in all eight search engines is three Examination of hyotheses In order to examine and test the roosed hyotheses, three statistical techniques were used: one-way ANOVA, two-way ANOVA, and indeendent-samle T-test. For the one-way ANOVA and the two-way ANOVA, we are assuming that the involved deendent variable is normally distributed, the oulation variances of the deendent variable are the same for all cells, and the case reresents random samles and the values of deendent variable are indeendent of each other. For the T-test, the assumtions are that the variable is normally distributed in the ou-

11 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Table 3 Distribution of test webage aearance in search engines AllWeb EntireWeb Google Lycos AltaVista Yahoo Inforsace/Fast Netscae W_P_1 W_P_2 W_P_3 W_P_4 W_P_5 W_P_6 W_P_7 W_P_8 W_P_9 W_P_10 W_P_11 W_P_12 W_P_13 W_P_14 W_P_15 W_P_16 W_P_17 W_P_18 W_P_19 W_P_20 W_P_21 W_P_22 W_P_23 W_P_24 W_P_25 W_P_26 W_P_27 W_P_28 W_P_29 W_P_30 W_P_31 W_P_32 W_P_33 W_P_34 W_P_35 W_P_36 W_P_37 W_P_38 W_P_39 W_P_40 W_P_41 W_P_42 W_P_43 W_P_44 W_P_45 W_P_46

12 702 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Across 0 SE Across 1 SE Across 2 SE Across 3 SE Across 4 SE Across 5 SE Across 6 SE Across 7 SE Across 8 SE Fig. 3. Webage frequency distribution across the search engines. lation, the variances of the normally distributed test variable are equal, and the case reresents random samles and the values of deendent variable are indeendent of each other. The measurement for the study was defined as the osition of a retrieved webage in a search engine. That is, the osition of a webage in a search engine results list was used to measure erformance of the test webages. It is clear that the definition of the measurement is measurable and manageable. The retrieved webages located in the to of the results list of a search engine have good visibility. In other words, the higher the osition of a retrieved webage in a search engine results list, the better its erformance and vice versa. A higher osition of a retrieved webage corresonds to lower value of the variable osition and a lower osition corresonds to a higher value of the variable osition. The significance level ()orsig. for all tests is Regardless of what secific statistic used, if or the sig. is smaller than 0.05, the finding is statistically significant and null hyotheses are rejected Examination of hyothesis 1 (H1) H1 states that there is no difference in search return erformance between webages with metadata elements and those without metadata elements. The test webages were simly divided into two grous with metadata and without metadata. For the first grou metadata was added in the metadata data title, metadata subject, or metadata descrition fields. For the second grou keywords with different frequencies aear in title, or fulltext, or both. The indeendent variables were the webages with metadata elements and those without metadata elements. The deendent variable was the webage return osition in a search engine results list. A T-test was used for this test because of the involvement of only two variables. Tables 4 and 5 show the statistical results for the T-test. The variable POSITION is defined the same as the returned webage osition in a search engine. TYPEs 1 and 2 refer to the webages without metadata elements and those with metadata elements, resectively. From Table 5, LeveneÕs F is statistically significant (F ¼ 13:969, ¼ 0:000 (<0.05)). Variances are significantly different so the assumtion of equal variances is violated. The null hyothesis was rejected. The means for the webages with metadata element and those without metadata element are and resectively (See Table 4). This shows that the webages with metadata

13 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Table 4 Grou statistics for H1 TYPE N Mean Std. deviation Std. error mean POSITION Table 5 Indeendent samles test for H1 LeveneÕs test for equality of variances POSITION Equal variances assumed Equal variances not assumed T -test for equality of means F Sig. t Df Sig. (twotailed) Mean difference Std. error difference 95% Confidence interval of the difference Lower Uer elements achieved better visibility erformance than those without metadata elements. The findings confirm the claim that imlementation of metadata in a webage would imrove its visibility in a search engine result. Fig. 4 dislays the results visually POSITION 0-10 N = TYPE Fig. 4. Boxlots of grou distribution changes for H1.

14 704 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Examination of hyothesis 2 (H2) H2 states that there is no difference in search return erformance among the webages with different numbers of metadata element combinations. In other words, it tests whether the number of metadata element combination effects webage return erformance. The indeendent variables were webages with different numbers of metadata element combinations. The variable TYPE in the following tables stands for the combinations. Its valid values are 1 (including metadata title, metadata subject, and metadata descrition), 2 (including metadata title and metadata subject, metadata title and metadata descrition, and metadata subject and metadata descrition), and 3 (including metadata title and metadata subject and metadata descrition). The deendent variable was the webage return osition in a search engine result. Due to the multile indeendent variables, a one-way ANOVA was used for this hyothesis. Tables 6 and 7 show the results for this test. Because the overall F is statistically significant as shown in Table 7 (F ¼ 5:795, ¼ 0:003 (<0.05)), a ost hoc test (the Tukey method) designed for situations in which the variances are unequal was conducted. The results of the Tukey HSD test are resented in Tables 8 and 9. It is very clear that the mean differences for the grou 3 (combination is 3) against grou 2 (combination is 2) and grou 1 (combination is 1) are ) () and ) (), resectively (see Table 8) (Note indicates significant difference in the table). Both are significant and negative, which indicates that the webages with keywords aearing in the metadata title field, metadata subject field and metadata descrition field achieved better visibility erformance than other ossible combinations. In Table 6, the standard deviation of grou 2 is relatively large ( ) and the difference between its lower bound and uer bound is also large ( ). It shows that the erformance of grou 2 (including metadata title and metadata subject, metadata title and metadata descrition, and metadata subject and metadata descrition) is not stable. Multile combinations and their inconsistent erformance in this grou may account for this henomenon. Contrary to exectations, grou 2 did not achieve better erformance than grou 1. Table 6 Descritive statistics for H2 N Mean Std. deviation Std. error 95% Confidence interval for mean Lower bound Uer bound Minimum Maximum Total Table 7 ANOVA for H2 Sum of squares Df Mean square F Sig. Between grous Within grous Total

15 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Table 8 Tukey HSD multile comarisons for H2 ðiþ TYPE ðjþ TYPE Mean difference ði JÞ Std. error Sig. 95% Confidence interval Lower bound Uer bound 1 2 ) ) ) ) ) ) ) ) ) * The mean difference is significant at the 0.05 level. Table 9 Tukey HSD homogeneous subsets for H2 TYPE N Subset for alha ¼ Sig Means for grous in homogeneous subsets are dislayed. (a) Uses harmonic mean samle size ¼ (b) The grou sizes are unequal. The harmonic mean of the grou sizes is used. Tye I error levels are not guaranteed. Table 9 shows that grous 2 and 1 and grous 3 and 1 form two homogeneous subsets whose means are not significantly different from one another. Fig. 5 is the visual dislay of the distribution of deendent variable across the grous POSITION 0-10 N = TYPE Fig. 5. Visual dislay of results for H2.

16 706 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Examination of hyothesis 3 (H3) H3 states that there is no difference in search return erformance among the webages with metadata title, webages with metadata subject, and webages with metadata descrition. The indeendent variables were webages with metadata title, webages with metadata subject, and webages with metadata descrition in a webage. The deendent variable was the webage return osition in a search engine result. Due to the multile indeendent variables, a one-way ANOVA was used for this hyothesis. Tables 10 and 11 demonstrate the results of the ANOVA test analysis. TYPEs 1, 2, and 3 in these tables stand for webages with metadata title, webages with metadata subject, and webages with metadata descrition, resectively. Since the overall F is significant as shown in Table 11 (F ¼ 14:604, ¼ 0:000 (<0.05)), the null hyothesis was rejected. Therefore a follow-u test (Tukey method) was conducted to determine the reasons for the rejection. The Tukey HSD analysis results are resented in Tables 12 and 13. From Table 12 grou 2 (metadata subject) against the grou 1 (metadata title) (ði JÞ ¼ 3:5222ðÞ) and against the grou 3 (metadata descritor) (ði JÞ ¼ 7:3906ðÞ) achieved better erformance than both the grous 1 and 3. That is, webages with metadata subject achieved better erformance than either webages with metadata title or webages with metadata descrition. The analysis shows that the metadata subject field is the most imortant and effective metadata element in terms of imroving webage visibility in a search engine results list. Notice that the mean difference for metadata title against metadata descrition is negative but not significant ()3.8684), indicating that metadata title field still achieved better erformance (but not statistically significant) than metadata descrition. After a close look at Table 10, it is aarent that erformance of web ages with metadata subject field is not only the best among the grous but also the most stable across all search engines (std deviation ¼ , lower bound ¼ , and uer bound ¼ ) and that Table 10 Descritive statistics for H3 N Mean Std. deviation Std. error 95% Confidence interval for mean Lower bound Uer bound Minimum Maximum Total Table 11 ANOVA for H3 Sum of squares Df Mean square F Sig. Between grous Within grous Total

17 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Table 12 Tukey HSD multile comarisons for H3 (I) TYPE (J) TYPE Mean difference (I J) Std. error Sig. 95% Confidence interval Lower bound Uer bound ) ) ) ) ) ) ) ) ) * The mean difference is significant at the 0.05 level. Table 13 Tukey HSD homogeneous subsets for H3 TYPE N Subset for alha ¼ Sig Means for grous in homogeneous subsets are dislayed. (a) Uses harmonic mean samle size ¼ (b) The grou sizes are unequal. The harmonic mean of the grou sizes is used. Tye I error levels are not guaranteed. erformance of webages with metadata descrition field is not only the worst but also the most unstable (std deviation ¼ , lower bound ¼ , and uer bound ¼ l5.7284). These findings suggest that webages with metadata subject and metadata descrition have strong and weak imacts, resectively, on their visibility in a search engine result. As is shown in Table 13, no more than one grou forms a homogeneous subset in this test. Fig. 6 is the visual dislay of the distribution of the deendent variables across the designed grous Examination of the hyothesis 4 (H4) H4 states that there is no difference in search return erformance among the webages with different metadata element combinations of metadata title, metadata subject, and metadata descrition. H4 is comlementary to H2. The indeendent variables were webages with different metadata element combinations of metadata title, metadata subject, and metadata descrition. The deendent variable was the webage return osition in a search engine result. Due to the multile indeendent variables, a one-way ANOVA was used for this hyothesis. In this case, the variable TYPE stands for the metadata element combination: metadata title (TYPE ¼ 1), metadata subject (TYPE ¼ 2), metadata descrition (TYPE ¼ 3), metadata title and subject (TYPE ¼ 4), metadata title and descrition (TYPE ¼ 5), metadata subject and descrition (TYPE ¼ 6), and metadata title and subject and descrition (TYPE ¼ 7).

18 708 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) POSITION 0-10 N = TYPE Fig. 6. Visual dislay of results for H3. Tables 14 and 15 dislay the results of the ANOVA test analysis. It is aarent that the overall F (F ¼ 9:237, ¼ 0:000 (<0.05)) is significant (see Table 15), therefore the null hyothesis is rejected. A Tukey HSD method was carried out to determine the reasons for rejection. The generated Tukey HSD analysis results are resented in Tables 16 and 17. The grou 7 (metadata Table 14 Descritive statistics for H4 N Mean Std. deviation Std. error 95% Confidence interval for mean Lower bound Uer bound Minimum Maximum Total Table 15 ANOVA for H4 Sum of squares Df Mean square F Sig. Between grous Within grous Total

19 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Table 16 Tukey HSD multile comarisons for H4 ðiþ TYPE ðjþ TYPE Mean difference ði JÞ Std. error Sig. 95% Confidence interval Lower bound Uer bound ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) * The mean difference is significant at the 0.05 level.

20 710 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Table 17 Tukey HSD homogeneous subsets for H4 TYPE N Subset for alha ¼ Sig Means for grous in homogeneous subsets are dislayed. (a) Uses harmonic mean samle size ¼ (b) The grou sizes are unequal. The harmonic mean of the grou sizes is used. Tye I error levels are not guaranteed. title and subject and descritor) has four significant and negative mean differences and two negative mean differences against the other grous; Grou 2 (metadata subject) has three significant and negative mean differences and one negative mean difference against the other grous; Grou 5 (metadata title and descritor) has one significant and negative mean difference and four negative mean differences against the other grous; and Grou 6 (metadata subject and descritor) has one significant and negative mean difference and two negative mean differences against the other grous. In other words, webages with keywords in metadata title and subject and descrition achieved the best erformance across the grous; followed by webages with keywords in metadata subject; then webages with keywords in metadata title and descrition; and last, webages with keywords in metadata subject and descrition. From Table 14, grous 2 (std deviation ¼ , lower bound ¼ , and uer bound ¼ ) and 5 (std deviation ¼ , lower bound ¼ , and uer bound ¼ ) achieved the most stable erformance in this test. On the other hand, grous 4 (std deviation ¼ , lower bound ¼ , and uer bound ¼ l3.0906) and 6 (std deviation ¼ , lower bound ¼ , and uer bound ¼ ) achieved the most unstable erformance in this test. Table 17 demonstrates that there are three homogeneous subsets: grou (7, 5, 2, 6, and 1), grou (6, 1, and 4), and grou (1, 4, and 3). Fig. 7 is the visual dislay of the distribution of deendent variable across the grous Examination of hyothesis 5 (H5) H5 states that keywords in metadata fields extracted from a title, a full-text, or both make no difference with resect to search return erformance in a search engine result. With this hyothesis we attemted to understand the imact of keywords in a webage used in metadata fields on the visibility in a search result. The indeendent variables were keywords in metadata extracted from the title, keywords in metadata extracted from the full-text, and keywords in metadata extracted from both title and full-text. The deendent variable was the webage return osition in a search engine result. Because of the multile indeendent variables, a one-way ANOVA was used for this hyothesis.

21 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) POSITION 0-10 N = 38 1 TYPE Fig. 7. Visual dislay of results for H4. In Table 18 the values in the column TYPEs 1, 2, and 3 reresent keywords in the metadata field extracted from title, keywords in the metadata field extracted from full-text, and keywords in the metadata field extracted from both title and full-text, resectively. Because of the significant overall F in Table 19 (F ¼ 131:494, ¼ 0:000 (<0.05)), keywords in metadata extracted from title, full-text, or both made significant differences in search return erformance in a search engine results list. Thus a follow-u test was conducted to identify the reasons for the difference. In Table 20, the mean difference (I J) for grou 1 (keywords extracted from title) against grou 2 Table 18 Descritive statistics for H5 N Mean Std. deviation Std. error 95% Confidence interval for mean Lower bound Uer bound Minimum Maximum Total Table 19 ANOVA for H5 Sum of squares Df Mean square F Sig. Between grous Within grous Total

22 712 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) Table 20 Tukey HSD multile comarisons for H5 (I) TYPE (J) TYPE Mean difference (I J) Std. error Sig. 95% Confidence interval Lower bound Uer bound 1 2 ) ) ) ) ) ) ) ) ) * The mean difference is significant at the 0.05 level. (keywords extracted from full-text) is ) () (negative and significant). The mean difference (I J) for grou 1 against grou 3 (keywords extracted from both title and full-text) is ) (negative). The mean difference (I J) for grou 3 against grou 2 is ) () (negative and Table 21 Tukey HSD homogeneous subsets for H5 TYPE N Subset for alha ¼ Sig Means for grous in homogeneous subsets are dislayed. (a) Uses harmonic mean samle size ¼ (b) The grou sizes are unequal. The harmonic mean of the grou sizes is used. Tye I error levels are not guaranteed POSITION 0-10 N = TYPE Fig. 8. Visual dislay of results for H5.

23 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) significant). This shows that keywords in metadata fields extracted from a title and keywords in metadata fields extracted from both title and full-text achieved better erformance than keywords in metadata field extracted from only the full-text. In order to effectively imrove webage visibility in search engine results lists, keywords of metadata elements should come from title, or from both title and full-text. Note that in Table 18 grous 3 (std deviation ¼ , lower bound ¼ , and uer bound ¼ ) and 2 (std deviation ¼ , lower bound ¼ , and uer bound ¼ ) achieved the steadiest erformance and the most unstable erformance across all search engines, resectively. Table 21 shows that there is only one homogeneous subset (Grous 1 and 3). Fig. 8 is the visual dislay of the distribution of deendent variable across the grous. 4. Conclusion This research identified influential factors of metadata imlementation that imact search engine otimization, analyzed their imacts on major internet search engines, and then recommended alicable and ractical methods for imroving search engine otimization in light of metadata imlementation. Toward these aims, 46 webages were derived and modified from a selected original webage, and were osted on the internet. The URLs of these rocessed webages were submitted to 19 search engines. The investigators used a simle formulated query to search the 19 search engines weekly. The returned results from each of the search engines were monitored and recorded. After 21 weeks of observation, eight search engines resonded to the submissions ositively and 28 osted webages aeared in our observation results lists at least once. All collected data were tabulated and classified. Three different statistical techniques were emloyed to examine the five hyotheses. Although all five hyotheses were rejected, the findings nevertheless suggest several otions to otimize webage visibility. Based on the statistical analysis discussed in the revious section, some key findings and recommendations for otimizing web site lacement in results lists are summarized below: (1) Do not use keywords in metadata fields that do not aear in either title or full-text of a webage. Keywords in metadata should come directly from the webage. (2) With resect to search engine indexing coverage, Google (47.83%), EntireWeb (36.96%), Allweb (32.61%), and Lycos (32.61%) achieved better erformance than other search engines. In other words, a webage osted in a ublic domain will most likely be crawled and indexed by Google, next EntireWeb, followed by Allweb and Lycos. (3) Webages with metadata elements achieved better visibility erformance than those without metadata elements. Imlementation of metadata in a webage, generally seaking, would increase its visibility in a search engine return list. (4) Webages with keywords aearing in three metadata fields (title field, subject field, and descrition field) achieved better visibility erformance than other ossible combinations such as metadata title and metadata subject, metadata title and descrition, and metadata subject and metadata descrition.

24 714 J. Zhang, A. Dimitroff / Information Processing and Management 41 (2005) (5) Webages with metadata subject achieve better the visibility erformance than either the webages with metadata title or the webages with metadata descrition in a webage. Metadata subject lays an extremely imortant role in imroving webage visibility in a search engine return list. (6) Webages with keywords in metadata title and subject and descrition achieved the best erformance across the grous; then web ages with keywords in metadata subject; then webages with keywords in metadata title and metadata descrition; and last webages with keywords in metadata subject and metadata descrition. (7) Keywords in the metadata elements extracted from title, and keywords in metadata elements extracted from both title and full-text achieved better visibility erformance than keywords in the metadata elements extracted from full-text. In general, if a webage is osted somewhere, it will most likely be indexed and included in Google. Metadata is a good mechanism to imrove the visibility of a osted webage in search engine results lists. The metadata subject field lays a more imortant role than any other metadata field. Keyword sources for metadata are also imortant. Make sure that these keywords are extracted from the webage itself. If the selected keywords for metadata are not reflected in either title or full-text of a webage, your efforts may be in vain. To maximize the effects, these keywords should come from both title and full-text. The findings of this research should benefit web ublishers, search engine designers and web information seekers. Future research directions might include, but are not limited to the following. An investigation of the imact of keyword frequency in metadata fields on the visibility of the webage. References Arasu, A., Cho, J., Garcia-Molina, H., Paecke, A., & Raghavan, S. (2001). Searching the Web. ACM Transactions on Internet Technology (TOIT), 1(1), Bilal, D., & Kirby, J. (2002). Differences and similarities in information seeking: children and adults as web users. Information Processing & Management, 38(5), Brasethvik, T. (1998). A semantic modeling aroach to metadata. Internet Research, 8(5), Burnett, K., Ng, K. B., & Park, S. (1999). A comarison of the two traditions of metadata develoment. Journal of the American Society for Information Science, 50(13), Cortez, E. M. (1999). Use of metadata vocabularies in data retrieval: from USDAÕs Research, Education, Economic Information System. Journal of the American Society for Information Science, 50(13), Duval, E., Hodgins, W., & Sutton, S. A. (2002 Aril). Metadata rinciles and racticalities. D-Lib Magazine, 8(4). Available: htt:// GVUÕs 9th WWW User Survey: Web and Internet Use Summary, (Available January 6, 2003). Available: htt:// Haltley, R. (2002). Making sure your Website is to. UK Newsquest Regional Press. H am al ainen, M., Whinston, A. B., & Vishik, S. (1996). Electronic markets for learning: education brokerages on the Internet. Communications of the ACM, 39(6), Hill, L. L., Janee, G., Dolin, R., Frew, J., & Larsgaard, M. (1999). Collection metadata solutions for digital library alications: Alexandria Digital Library. Journal of the American Society for Information Science, 50(13), How easy are you to find? Available: htt:// [7 January 2003].

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