Several calculations have been attempted to measure the cost of reserves. The traditional one is the spread between government debt and the yield on reserves. The caveat is that higher reserves can decrease the perception of risk and thus the government bond interest rate, so this measures can overstate the cost. Alternatively, another measure compares the yield in reserves with the alternative scenario of the resources being invested in capital stock to the economy, which is hard to measure. One interesting measure tries to compare the spread between short term foreign borrowing of the private sector and yields on reserves, recognizing that reserves can correspond to a transfer between the private and the public sectors. By this measure, the cost can reach 1% of GDP to developing countries. While this is high, it should be viewed as an insurance against a crisis that could easily cost 10% of GDP to a country. In the context of theoretical economic models it is possible to simulate economies with different policies (accumulate reserves or not) and directly compare the welfare in terms of consumption. Results are mixed, since they depend on specific features of the models.