Do collection expenditures predict public library circulation? Evidence from longitudinal data

This study examines the relationship between collection expenditure, a core financially input in public libraries, and service outcomes as measured by annual circulation. Using panel data from 1112 public libraries in Korea drawn from the National Library Statistics System for 2021–2024, the analysis applies a Random Intercept Cross-Lagged Panel Model (RI-CLPM) to disentangle between-library differences from within-library year-to-year changes. Results showed strong temporal stability in circulation, with prior-year circulation significantly predicting subsequent-year circulation (autoregressive effect). The contemporaneous association between collection expenditure and circulation was statistically significant but modest in magnitude, suggesting the need to consider time-lagged effects. Under an equality-constrained observed-score lagged model (which does not separate between- and within-library components), positive lagged effects were observed: higher collection expenditure in a given year predicted higher circulation in the following year. At the within-library level in the RI-CLPM, year-to-year increases in collection expenditure were significantly associated with increases in circulation. In substantive terms, a 1 million Korean won (KRW 1,000,000) increase in a library’s collection expenditure was associated with an increase of approximately 112 loans in the subsequent year. These findings indicate that expanding collection expenditure is likely to be linked to improved use outcomes and can serve as policy-relevant evidence to inform discussions on budget allocation and performance management for public library collections.