First Advisor

Jiunn-Der (Geoffrey) Duh

Date of Award

2025

Document Type

Report

Degree Name

Master of Science (M.S.) in Geographic Information Science

Department

Geography

Language

English

Subjects

Geographic information systems -- Analysis, Wildfire risk -- United States

Abstract

Collecting spatial information using maps is a recurring need in research and policy (Evers, 2020; Gottwald et al., 2016; Hitchins, 2018; Tang & Liu, 2016). Survey participants frequently abandon map-based surveys at the first mapping task (Poplin, 2015). In his survey of wildfire risk management personnel, Evers (2020) applied a simplified web-mapping interface that uses circles as the sole input geometry for all spatial representations. The current project examines an updated version of this web map. An anonymous survey gathered data from participants who completed six mapping exercises within Portland, Oregon, and provided feedback on the survey experience. A working hypothesis proposed that greater experience with web maps and/or GIS, higher familiarity with the target locations in the survey, or time lived in the region, would improve spatial accuracy. Submissions were compared to target geometries using three metrics: centroid distance, area coverage, and shape similarity. Participants successfully marked point and area locations with 90% and 95% positional accuracy, respectively. The effects of hypothesized factors on accuracy were either nonexistent or statistically insignificant. Linear and logit regression analysis showed that map display resolution was significantly associated with data quality (p< 0.001), explaining 32.6% of variance in centroid distance when a Box-Cox transform was applied (λ=-0.0202, p< 2e-16). Participant-specified regions exceeded target size on average by a factor of 1.5 when boundaries were visible. The effect of input device on positional accuracy approached statistical significance (p=0.056), with phone users exhibiting higher error rates (12.5% vs. 7.2% for laptops and 1.9% for desktops). These findings validate the circle-based approach for collecting reliable spatial data with minimal training, while suggesting specific interface improvements such as enforcing minimum zoom levels. Results have immediate application for wildfire risk management data collection and broader implications for PPGIS applications at similar map scales.

Rights

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Comments

A GIS practicum report submitted in partial fulfillment of the requirements for the degree of Master of Science in Geographic Information Science.

Persistent Identifier

https://archives.pdx.edu/ds/psu/44091

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