Urban planning is an interdisciplinary field, focused on understanding human settlement patterns [1
]. Planning is a specialized and relatively small discipline that draws on design (e.g., architecture), policy (e.g., public administration), and social science (e.g., geography). Like other social sciences, urban planning scholars disseminate their research in a wide array of academic journals. For just over 1100 urban planning faculty in the USA and Canada, there are over 300 journals where their publications appear. It is difficult to say whether this is a significantly large number of outlets without similar metrics from other disciplines. However, the objective of this article is to examine which research topics are of interest to current urban planning faculty in North America, and not a comparison to other disciplines. The purpose is to identify prominent topics so that planning academics can reflect on whether these are the issues that should be receiving our attention. The analysis concentrates on faculty in urban planning programs and their publication activities, and not what is being published about urban planning topics in general. This provides the opportunity for planning to consider its scholarly priorities as we look to the future of urban planning and urban science research.
With urban planning interests representing several disciplines, we suspect that there is a shifting hierarchy of topics over time. These include, but are not limited to, changing perspectives on infrastructure policy, architecture, social conditions, environmental conditions, economic activity, and governance—all of these representing significant aspects of urban systems. Not all of these are given equal attention over time, as particular concerns or interests are more visible at certain times compared to others. From the public’s perspective, these interests are being driven by changing policies or politics, and by the flow of information from sources, such as the news media. From an academic and institutional standpoint, themes of research are certainly influenced by the availability of funding and the priorities of funding organizations [2
]. While there are no comprehensive data sources about funded research activities related to urban planning, it would be interesting to know how or whether these topics differ from those of scholarly output. This remains a topic for future research.
Within urban planning, there is also the question of how academic research represents the needs of the practicing professionals [4
]. Planning professionals are confronted with new and different types of urban questions, as well as seeking solutions to on-going questions. Loh [6
] argues that “planning is very much an action-oriented field” and therefore, research “not closely focused on what planners actually do is of limited relevance to the profession” (p. 25). Urban planning scholars have long contributed knowledge to the planning profession through their teaching, research, and service activities, while at the same time meeting traditional academic expectations through scholarship [7
]. Planning students seek professionally-oriented training, and academic planning programs are expected to connect directly with local communities through their service and outreach activities [8
]. However, the question remains whether planning academics are more responsive to topics when funding is available, when research is needed by the profession, or when the topic is of academic interest. Some have argued that placing scholarship as a priority over teaching and service in planning programs is a result of institutional pressures for faculty having doctorates rather than professional certification. As Krumholz noted, the emphasis on “a productive history of publication in refereed journals,” contributes to a divide between planning research and practice [10
Citation analysis has an extensive literature documenting citation practices across disciplines, as well as meticulous discussion of measurement and evaluation [11
]. Citation analysis is a way to evaluate scholarship to gauge prominence and productivity, but often excluding other dimensions, such as visibility and impact [15
]. Citation analysis is also benefitting sophisticated text analytics techniques that move beyond extracting and counting citation to determining context and intent for citations [14
]. The following provides a brief discussion and background on citation data, citation analysis, and urban planning scholarship.
This analysis uses citation metadata and counts from Google Scholar (GS). Many researchers have examined GS for citation analyses by making comparisons to the other prominent sources of citation data (such as Scopus and Web of Science (WoS)). One concern that has arisen is about GS’s coverage of scholarly publications relative to that of Scopus or WoS [16
]. However, these issues are likely discipline-specific, with many examples highlighting GS’s reliability for topics ranging from oncology and condensed matter physics [20
], business and economics [21
], health and medical research [22
]. Meta-analyses are useful for illustrating patterns in bibliometric performance by examining different data sources and analytical methods [23
]. Many of the analyses comparing GS with Scopus and WoS concentrate on the difference in the number of citations rather than the accuracy of these data at the for individual authors. However, to assess the accuracy of citation counts for an author, a verified list of publications, such as from a current CV (Curriculum Vitae) would have to be compared to those listed in citation databases. This is not presently feasible because there are no centralized sources of confirmed CV data or publication records that can be matched to those in citation databases.
GS includes “non-traditional” publications unlike Scopus and WoS [25
]. The presence of non-peer-reviewed publications in GS is a relevant question, when considering scholarly citation counts. The inclusion of gray literature, for instance, has been argued to have a greater reach and impact compared to pay-wall-protected publication and citation data from major publishers. Professionally oriented disciplines like urban planning produce gray literature that is research-based and reflects the scholarly process of particular value to allied professions, and therefore, reflects academic rigor and impact [27
]. Finally, Pauly and Stergiou [30
] stated that “free access to these data provided by Google Scholar offers an avenue for more transparency in tenure reviews, funding and other science policy issues, as it allows citation counts, and analyses based thereon, to be performed and duplicated by anyone” (p. 2). This is a strong case for GS as a source of citation analysis and the fact that it includes gray literature is particularly pertinent to planning academics.
As mentioned earlier, urban planning draws upon a diverse range of disciplines and expertise. These form urban planning subfields that are reflected in the types of publication topics, as well as the breadth of journals where these publications appear. Of the few journal articles about urban planning citation activity beginning with Stiftel, Rukmana, and Alam [31
] (followed several years later by Sanchez [32
], Pojani et al. [33
] and Stevens et al. [34
]), only Stevens et al. have explicitly tried to measure topical differences within urban planning citation patterns. In their analysis of factors affecting urban planning citations, they examined whether the publication topics were related to thirteen selected topics. They found that compared to “transportation”, nearly all of the other 12 were cited less frequently. Compared to the current analysis, Stevens et al. had a sample of 580 compared to nearly 15,000 in this analysis. In addition, Stevens et al. used manual, single-label topic classification versus multi-label in this analysis. The sample size issue could introduce bias by underrepresenting certain planning topics.
The bibliometric literature has recognized the differential rates of citation by topics, following the assumption that certain sub-fields are more popular, have more publications, and therefore, greater chances of citation [35
]. One methodological issue is how to classify or categorize publications so that citation rates can be accurately compared. This includes an approach to normalize citation counts based on some of these factors [36
]. These methods include topic analysis [37
], author-provided keywords [38
], thematic analysis [39
], or based on categorization defined at submission by authors or journal editors. Topics and keywords restricted by journals can have a limiting effect on topic or theme classification through unintentional exclusion. An alternative would be to analyze abstracts for these purposes, but it greatly increases the data collection and analysis task for the uncertain benefit to the classification process. In addition, titles are consistently available across publication types (i.e., journal articles, books, or reports) where abstracts and keywords are not. Therefore, titles provide a rich data source for the current analysis.
The title of a publication is considered to be important for not only indicating content, but also for attracting attention [40
]. While the author provided keywords are frequently used for discovery, titles themselves can distill several dimensions of a publication, including subject, method, geographic context, and results [42
]. Because distinct keywords may not convey an overall theme, such as what can be represented in the sentence form of a title. This has to do with the linguistic structure of a title not intended by keywords [43
]. However, Levy and Ellis [44
] suggest that the author provided keywords may be buzz-word laden, and perhaps unreliable in the long-term. In addition, besides the information retrieval aspects of titles, bibliometricians have examined how title characteristics correlate with citation rates [45
]. Such analyses include title length, punctuation, structure, use of acronyms, and descriptiveness. However, in cases where title attributes are correlated with higher citation rates, it has not been suggested that this somehow indicates a higher level of publication quality.