Progress 08/01/24 to 07/31/25

Outputs
Target Audience: The target audience for this work includesacademic researchers, federal and state policymakers, and environmental agency analystsengaged in nonmarket valuation, recreation-demand modeling, and benefit-cost analysis. Specifically, the project's findings are designed foreconomists and data scientistsstudying ecosystem services and the use of big-data sources such as cellphone mobility information for environmental valuation, as well as fordecision makers at agencies such as USDA, EPA, DOI, and state natural resource departmentswho rely on robust, standardized methods to quantify the social benefits of conservation and recreation investments. In addition,graduate students and technical practitionersworking in environmental economics and policy analysis constitute an important secondary audience, as the project's outputs--including standardized protocols, open-source methods, and empirical applications--offer a transferable framework for advancing data-driven, policy-relevant valuation of nature-based recreation and environmental quality. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provides extensive opportunities fortraining and professional developmentacross multiple levels of engagement. Graduate students and early-career researchers are gaining hands-on experience in cutting-edgedata science applications for environmental economics, including large-scale data cleaning, geospatial analysis, and estimation of discrete choice and welfare models using mobility datasets such as SafeGraph, Spectus, and Advan. Students likeDimitris Friesen (UW-Madison)andLuc Esprabens (Cornell University)are developing independent research papers--on Iowa lake recreation and national park option prices, respectively--that both advance the field and serve as components of their graduate dissertations. How have the results been disseminated to communities of interest?Conference presentations and individual seminars. What do you plan to do during the next reporting period to accomplish the goals?The upcoming year will focus on completing core deliverables and expanding the project's national applications. Key planned milestones include: Final acceptance and production of theLand Economicsspecial issue (by February 2026). Completion of Friesen's revised Iowa Lakes application and comparative validation with survey data. Expansion of national-scale Spectus data extraction and representativeness analysis. Publication of a best-practice protocol paper suitable for Review of Environmental Economics and Policy. Development of an ArcGIS-based visualization portal for recreation benefits transfer. Preparation of student dissertation proposals and multi-site comparative applications. The team will further refine and extend the option price framework developed in the Economic Value of Nature in Times of Stress' paper to other environmental amenities, including freshwater lakes and wildfire-affected areas.

Impacts
What was accomplished under these goals? The project continues to make strong progress toward its overarching objective of developing standardized protocols and validity tests for nonmarket valuation using large-scale cellphone mobility data. The team has successfully coordinated an emerging network of scholars and practitioners applying mobility data to recreation-demand modeling, fostering collaboration across universities, agencies, and data providers. During this reporting period, progress was achieved in several core domains: the advancement of the Land Economics special issue on recreation demand modeling, the completion of major data integration steps for the Iowa Lakes and national datasets, the development of applied studies using SafeGraph and Spectus data, and the continued mentoring and research output from the graduate research team. Collectively, these milestones strengthen the foundation for standardized benefit-transfer applications using mobility-based visitation data across the United States. A major methodological advance during this reporting period was achieved through the study titled *The Economic Value of Nature in Times of Stress: Option Prices of the U.S. State Park System* (Esprabens, Del Rossi, Kling, Rudik, and Zhang, 2025). This paper applies large-scale Advan cellphone mobility data to derive empirical estimates of option prices (OP) and expected compensating variations (CV) under uncertain states of the world, such as pandemic versus non-pandemic conditions. It represents the first implementation of the theoretically correct ex ante welfare measure (OP) using revealed-preference data. The findings provide critical insights for valuing nature-based recreation under uncertainty, complementing the Land Economics special issue and reinforcing the project's leadership in advancing mobility-based welfare measurement frameworks. 2.Land EconomicsSpecial Issue (Vol. 102, No. 3, August 2026) The forthcoming Land Economics special issue titled 'Recreation Demand Modeling Using Cellphone Mobility Data,' co-edited by Phaneuf, Zhang, and Ji, is on track for publication in August 2026. Ten papers are currently under consideration; each having received revision invitations during summer 2025. Revised manuscripts are due October 31, 2025, with final acceptance and production targeted for February 2026. The special issue builds upon outcomes from the January 2025 Land Economics Mobility Data Workshop, which convened more than twenty research teams and agency partners to evaluate emerging practices for estimating recreation demand from smartphone-based visitation data. Collectively, these papers address topics ranging from water-quality valuation and beach advisories to wildfire smoke impacts, congestion effects, and environmental justice dimensions in recreation access. A second informal workshop is planned for January 2026 to synthesize lessons learned and develop a concise synthesis article for publication. This will help institutionalize best practices in zero-share correction, causal inference, and welfare estimation for big-data applications in environmental valuation. 3. Iowa Lakes Mobility Data Application (Friesen 2025) The Iowa Lakes mobility data application, led by PhD student Dimitris Friesen at the University of Wisconsin-Madison, represents the first empirical implementation of the project's data-integration framework. His study, titled 'Frequent Visitation and Valuing Environmental Quality,' employs Cuebiq mobility data (2019-2022) for approximately 143 Iowa lakes, combined with detailed water quality indicators (Secchi depth and dissolved oxygen) from the Iowa DNR's Iowa Lakes Project. Friesen's analysis uses a Random Utility Maximization (RUM) model to estimate willingness to pay for water quality improvements. A baseline model yields a mean per-trip willingness to pay of approximately $9.40 for a one-meter improvement in Secchi Disk Depth, which aligns with prior survey-based estimates from the Iowa Lakes Survey. Early validity checks comparing mobility-based and survey-based visitation shares show a strong positive correlation across lakes, supporting the reliability of the mobility-derived data. Ongoing work focuses on addressing parameter instability in the heterogeneous models and improving treatment of measurement error in travel cost and environmental quality variables. The revised version of this paper, due October 2025, will serve as a cornerstone for the project's comparative validity objective (Objective 3). Longer term, this analysis will inform Dimitris Friesen's dissertation proposal in spring 2026, which will integrate survey, mobility, and property-value models. 4. Data Integration and Methodological Development Under the direction of Co-PI Yongjie Ji (Iowa State University, CARD), substantial progress has been made in data processing, integration, and methodological development. Major achievements include: Cleaning and standardization of the 2019 Iowa Lakes Survey dataset. Construction of geospatial lake polygons used by Friesen to extract and match cellphone-based visitation data. Acquisition of Iowa DNR water quality data (nutrients, chlorophyll-a, and Secchi depth) spanning 2000-2024. Development of initial documentation for standardized visitation estimation procedures. In the upcoming reporting period, Ji's team will complete the integration of survey, mobility, and water quality datasets into a unified analytical framework, conduct preliminary analyses linking environmental quality to visitation behavior, and prepare visualization materials for dissemination through an interactive web portal.

Publications

• Type: Peer Reviewed Journal Articles Status: Accepted Year Published: 2025 Citation: Zhang, Wendong and WAN, Xibo and Ji, Yongjie and Fan, Wenran, Uncovering Disparities in Water-Based Outdoor Recreation using Cell Phone Mobility Data (September 26, 2024). Cornell SC Johnson College of Business Research Paper (forthcoming), Environmental Research Letters (forthcoming), Available at SSRN: https://ssrn.com/abstract=4968985 or http://dx.doi.org/10.2139/ssrn.4968985