Transaction Log Analysis of a Japanese Mobile Phone OPAC
Harumi MURAKAMI1*, Chizu KANATA2
1Graduate School for Creative Cities, Osaka City University,3-3-138, Sugimoto, Sumiyoshi, Osaka 558-8585 Japan
2Chuoystem Corporation, 1-9-15, Kitahama, Chuo, Osaka 541-0041 Japan* Correspondence should be addressed to harumi@media.osaka-cu.ac.jp

Abstract
We analyzed the transaction log of Osaka City
University’s Mobile Phone Online Public Access
Catalog (OPAC) and found the following results:(1) The average number of input terms was 1.4, and92.2% of the searches only used one or two terms;(2) An automated re-search facility improved thezero-hit problem by 31.7%. We concluded that thenumber of input terms resembled Japanese WebOPACs, Web searches, and mobile search engines.
Two results reflect that Japanese is an agglutinative
language: the number of input terms is half ofwestern Web-OPACs and Web search engines, andan automated re-search facility is useful.

Introduction
In Japan mobile phone OPACs (Online Public
Access Catalog) have been rapidly spreading inuniversity and public libraries. Analyzing how
mobile phone OPACs are used is crucial work inthe so-called “Mobile 2.0” age.
Transaction log analysis has been a usefulapproach to investigate user search behavior. Much
work has analyzed user behaviors for databases,OPACs (Peters, 1989), and Web search engines(Kashman et al., 2006) by transaction log analysis.
Research into the use of mobile search engines has
also been reported. However, the search behavior
for mobile phone OPACs has not been thoroughlyinvestigated.
In this paper, we analyzed the transaction log ofOsaka City University’s Mobile Phone OPAC
(hereafter OCU-Mobile-OPAC) for 2005. Thesystem is currently open to the public as a pilot test,
and the number of users is small. However, webelieve that investigating system use is valuable
because scant work in the world has investigated
how users utilize mobile phone OPACs.

Overview of OCU-Mobile-OPAC
OCU-Mobile-OPAC is the mobile phone OPAC ofOsaka City University (Figure 1). Its features
include the following: (1) a simple keyword searchfacility with additional narrower search by adding
keywords; (2) one result page that displays amaximum of 25 results; (3) an “automated research facility” that breaks Japanese queries intomorphons using morphological analysis and researches using these terms with an “AND” searchfor solving “zero-hit problems”; and (4) anAmazon search facility that displays Amazon data(customer opinions, etc.) when requested.

MethodLog Data
We analyzed OCU-Mobile-OPAC’s transaction
log for 2005. Date, time, IP addresses, mobile
phone numbers, operations, etc. are recorded in thelog data. The system can be used by PCs, butaccess logs by PCs can be removed by checking
whether the data have mobile phone numbers.

Identifying Sessions
The biggest difference between logs by PCs andmobile phones is that mobile phone numbers arerecorded by access from mobile phones. We
exploit this advantage to identify sessions using thefollowing procedure: If a mobile phone number ofan access is identical as the previous access, andthere is a 15-minute interval from the previousaccess, the access is included in the same session
as the previous access; otherwise, the access istreated as a new session.

Floor Image

KeywordSearchAmazonInformation

Search Results
Bibliographic
Information(a) Keyword search screen: users can input a word or phrase and execute a search.
(b) Search results screen: search results are displayed. Users can select a result (title), input a word or phrase into
the search box and execute a narrower search, or return to the keyword search screen.
(c) Bibliographic information screen: displays such information of the selected title. Users can display a floor
image where the title is located, view Amazon information of the selected title, or return to the keyword search
screen.

Figure 1:Screen example of OCU-Mobile-OPAC.

ResultsOverview
The number of accesses (identical to operations)from mobile phones was 1,338. The number ofidentified sessions was 298. The number ofdifferent mobile phones was 43.
Figure 2 shows an overview of operations. 657(49.1%) were search, 494 (36.9%) displayed
bibliographic information, 95 (7.1%) displayed
Amazon information, 50 (3.7%) were top pageaccesses, 27 (2.0%) displayed subsequent pages,
and 15 (1.1%) displayed floor images.

Display
Next
Top
2.0%
3.7%
Display
Amazon
7.1%
DisplayBib
36.9%

Display
Image
1.1%
Search
49.1%

Figure 2: Overview of accesses (operations).

81.0% (132/163) of the search operations that
contained more than 25 search results displayed
only the first page.
Narrower searches by adding keywords were10.5% (69/657) of the search operations.

Search Results
Figure 3 shows the ratio of number of search
results. 108 (16.4%) were zero hits, 117 (17.8%)
were only 1 hit, 269 (40.9%) were 2-25 hits, 140(21.3%) were 26-999 hits, and 23 (3.5%) weremore than 999 hits.
In the case of zero hits or more than 999 hits
(19.9%), no result is displayed in OCU-MobileOPAC.
Displaying subsequent pages was performed 27times in 26-999 hits (140 times). We therefore
found that 80.7% of the operations of 26-999 hits
only displayed the first page.
The automated re-search facility was performed
167 times. For 167, the number of displayed search
results (i.e., 1-999 hits) is 53. In other words, theautomated facility improved the zero-hit problem
31.7% (53/167).
1000‐ hits
3.5%
0 hit
26‐999 hits 16.4%
21.3%

1 hit
17.8%

2‐25 hits
40.9%

Figure 3: Number of search results.

Queries
580 were Japanese (88.8%), 57 were otherlanguages (alphabet) (8.7%), and 16 were a
mixture of Japanese and other languages (alphabet)(2.5%). English was the most common otherlanguage.
Input Terms The concept “term” differs bylanguage. We define a term as “a character string
segmented by spaces, commas, periods, or othersymbols.” The average number of input terms(terms included in queries) was 1.4.
Figure 4 shows how many terms are included inthe queries. 429 (65.3%) were searched by oneterm. 177 (26.9%) were searched by two terms. 40(6.1%), 5 (0.8%), and 2 (0.3%) were searched bythree, four, five terms, respectively. Four queries
included nothing (0.6%). In other terms, 92.2%
was searched by one or two terms.
4 terms 5 terms
0.3%
0.8%
3 terms
6.1%
2 terms
26.9%

0 term0.6%

1 term65.3%

Figure 4: Input terms.
The number of terms of the longest query was 5
both in Japanese and the other languages. The
number of terms of the shortest query was 1 bothin Japanese and in the other languages.
Input Characters The average number of input
characters (characters included in queries) was 6.5
when including spaces, and 6.1 when not including
them.The number of characters of the longest
query in Japanese was 22 and other languages was32 (not including spaces). The number ofcharacters of the shortest query was 1 both inJapanese and other languages.

Discussion
We discuss the features of the use of a Japanese
mobile phone OPAC by concentrating on the input
terms for comparison with other search systems. In
our result, 1.4 is the average number of input
terms: 1 term (65.3%) and 2 terms (26.9%).
Taneichi and Itsumura (2007) reported 1 term(66.5%), 2 terms (27.2%), 3 terms (5.9%), andmore than 3 terms (0.3%) for a Japanese college
library Web-OPAC in 2004-2006.
Lau & Goh (2006) reported 2 terms (34.1%), 1term (23.6%), and 3 terms (17.3%) for a

Singaporian university library Web-OPAC. The
average number of input terms was 2.86.
Inoue reports that 1.45 terms were input inYahoo! Japan on February 2006 (“Internet Watch,”(n.d.)).
According to a report by OneStat.com(“OneStat.com,” (n.d.)), two or three terms areusually input in Web search engines in ninewestern countries. In July 2006, the frequency of
input terms was 2 terms (28.9%), 3 terms (27.9%),
4 terms (17.1%), and 1 term (11.4%).
A questionnaire survey in 2006 (“WebMarketing Guide,” (n.d.)) showed that 88.3% ofusers input one or two terms in Japanese mobile
search engines: 1 term (47.2%) and 2 terms(41.5%).
Concerning input terms, our result resembles
Japanese Web-OPACs, Web searches, and mobile
search engines. The number of input terms isalmost half of western Web-OPACs and Websearch engines.
The above result reflects that Japanese is anagglutinative language. For the same reason, anautomated re-search facility was also useful.

SummaryWe analyzed the transaction log of Osaka City
University’s Mobile Phone OPAC for 2005 andfound the following results: (1) The average
number of input terms was 1.4, and 92.2% of thesearches only used one or two terms; (2) Anautomated re-search facility improved the zero-hit
problem by 31.7%. We concluded that the numberof input terms resembled Japanese Web-OPACs,
Web searches, and mobile search engines. Tworesults reflect that Japanese is an agglutinative
language: the number of input terms is half ofwestern Web-OPACs and Web search engines, andan automated re-search facility is useful.

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