In a seminal article, Weingast et al. (1981) argue that there is a positive relationship between legislature size and inefficiency in public expenditures. Their proposition is currently known as the "law of _1/n_" and has been widely cited by scholars in political science and public administration. However, recent studies have questioned the validity of the theory. In this paper, we estimate the first meta-analysis of the relationship between the number of legislators and public spending. Based on a sample of 26 empirical studies, we find little effect of legislature size on government budgets. The available evidence suggests that, if such an effect exists, it is driven by an increase in the upper chamber, but there is considerable heterogeneity in the results. Our meta-regressions also indicate that study coefficients vary significantly according to modelling specifications, such as estimation method or variable selection.

In path-breaking work, Weingast et al. argue that there is a positive relationship between legislature size and inefficiency in public expenditures. Their proposition is currently known as the ‘law of 1/n’ and has been widely debated in political science and public administration. However, recent studies have questioned the validity of the theory. In this letter, we conduct the first meta-analysis that assesses the generality of the ‘law of 1/n’. Based on a sample of thirty articles, we find no robust evidence suggesting that legislature size has either a positive or a negative effect on government budgets. Yet, the aggregate results mask considerable heterogeneity. Our findings provide moderate support for the ‘law of 1/n’ in unicameral legislatures and in upper houses, but they also indicate that studies using panel/fixed-effects models or regression-discontinuity designs report negative public spending estimates. We find only limited evidence that electoral systems impact public spending, which suggests that proportional representation systems may not be more prone to overspending than majoritarian ones.