Details

Autor(en) / Beteiligte

• Teka, Brhane Bahrishum

Titel

A Systematic Comparison of Spatial Search Strategies for Open Government Datasets

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2019

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Datasets produced or collected by governments are being made publicly available for re-use. Open government data portals help realize such reuse by providing list of datasets and links to access those datasets. This ensures that users can search, inspect and use the data easily. With the rapidly increasing size of datasets in open government data portals, just like it is the case with the web, finding relevant datasets with a query of few keywords is a challenge. Furthermore, those data portals not only consist of textual information but also georeferenced data that needs to be searched properly. Currently, most popular open government data portals like the data.gov.uk and data.gov.ie lack the support for simultaneous thematic and spatial search. Moreover, the use of query expansion hasn't also been studied in open government datasets. In this study we have assessed different spatial search strategies and query expansions' performance and impact on user relevance judgment. To evaluate those strategies we harvested machine readable spatial datasets and their metadata from three English based open government data portals, performed metadata enhancement, developed a prototype and performed theoretical and user evaluation. According to the results from the evaluations keyword based search strategy returned limited number of results but the highest relevance rating. In the other hand aggregated spatial and thematic search improved the number of results of the baseline keyword based strategy with a 1 second increase in response time and but decreased relevance rating. Moreover, strategies based on WordNet Synonyms query expansion exhibited the highest relevance rated rst seven results than all other strategies except the keyword based baseline strategy in three out of the four query terms. Regarding the use of Hausdor distance and area of overlap, since documents were returned as results only if they overlap with the query, the number of results returned were the same in both spatial similarities. But strategies using Hausdor distance were of higher relevance rating and average mean than area of overlap based strategies in three of the four queries. In conclusion, while the spatial search strategies assessed in this study can be used to improve the existing keyword based OGDs search approaches, we recommend OGD developers to also consider using WordNet Synonyms based query expansion and hausdor distance as a way of improving relevant spatial data discovery in open government datasets using few keywords and tolerable response time.