Economics CWU Student Price Index Project: Cost of Living in 2025 ‡ Ririna Yamamoto, Diego Garza Project Mentor(s): Yurim Lee, PhD
The Central Washington University (CWU) Student Price Index (SPI) project measures the cost of living in Ellensburg, Washington. The SPI is valuable because it analyzes a market basket of goods that are curated to the unique spending of college students. Each month, students collect prices on the items included in the basket and construct the price index based on the assigned weights on expenditures per category. Through this data, the team calculates inflation rates and analyzes how student expenditures are affected by price fluctuations, consistent with the methodology employed by the Bureau of Labor Statistics for the Consumer Price Index. The annual data for 2025 shows that the inflation rate measured by the SPI decreased through the year, starting at 9.4% in January and ending at -3.7% in December. On the other hand, the annual inflation rate measured by the CPI was consistently between 2% and 3.5% throughout the year. Looking at the monthly data in 2025, the SPI fluctuated significantly, with a 16.1% spike in July and a 15.3% drop in October; however, the CPI was stable throughout the year between -0.1% and 0.7%. Within the market basket that the SPI measures groceries were among the most volatile with a standard deviation of 0.21. This is the result of the avian flu that decreased the supply of eggs through January 2025 and June 2025. Furthermore, apart from groceries, the most volatile categories are those that are affected by seasonality, such as beer and school supplies. Presentation Type: Pre-Recorded Presentation (https://www.youtube.com/@cwusource5518) Keywords : Cost of Living, Inflation Rate, Consumer Price Index, Supply and Demand, Student Price Index SOURCE Form ID: 99
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