Coefficient estimates for unemployment are the only ones within each choice set that are highly sensitive to the inclusion of fixed effects and other controls. In the very simple models without fixed effects or controls, these coefficients capture, to a large extent, pure cross-sectional variation. Our hypothesis, however, is not related to the base level of unemployment (associated with structural problems of the economy that cannot be addressed effectively through multi-bi aid), but to temporary downturns of the economy that may lead donor country governments to use their foreign policies to signal their concern for increasing employment. This reasoning is supported by regressions that control for donor fixed effects. When the cross-sectional variation is controlled for by the fixed effects (with or without additional controls), the coefficients turn positive and partly significant in both choice sets for the smaller two fund types. While this pattern of coefficients is consistent with our hypothesis, Wald tests show that the differences between them are not always significant (Tables 3 and 4).

Prior pledges at the G8 should reflect a common interest of at least some donors in certain sectors. As expected, this variable is associated with increased participation in (small or large) MDTFs as opposed to SDTFs; for the latter, the coefficient is always negative but in most cases insignificant. Results for the G8 variable are statistically significant more often for choice set B than for A. This pattern can also be seen from the corresponding Wald tests (Table 4), which indicate positive and significant effects of G8 pledges at each step, moving from SDTFs to small MDTFs to large MDTFs.

An even more robust relationship is observed between global activities and trust fund participation. In line with our hypotheses, no matter the specification and the choice set considered, trust funds supporting global public goods provision tend to include multiple donors. The probability of participating in a large MDTF increases by more than 10 percentage points in choice set A (6 or 7 percentage points in choice set B) if it funds global activities. This effect is significantly larger than the corresponding effect on small MDTFs funds (1 or 2 percentage points in choice set A; 0.6 or 0.7 percentage points in choice set B), which is in turn significantly higher than for SDTFs (negative coefficients, not significantly different from zero). All differences across trust fund types are strongly significant, as shown by Wald tests in Tables 3 and 4.

Results are similarly strong for trust funds with a focus on fragile states, which tend to take the form of large MDTFs, consistent with the view that risk sharing is an important consideration for these funds. For funds supporting fragile states, the propensity to become a member increases by 6 or 7 percentage points in choice set A if it is a large MDTF, and by 2.2 or 2.3 percentage points in choice set B. According to the Wald tests, differences across all fund types are significant in choice set B (Table 4), while the test cannot establish significance for the smaller two fund types in choice set A (Table 3).

Overall, these tests mostly support our hypotheses. Results for preference heterogeneity (as measured from bilateral sectoral allocations) and the indicator variables for global activities and fragile states are particularly robust. We also have a tentative explanation for why some relationships do not turn out as strongly as expected. In reality, the type of fund chosen by a donor not always allow us to infer its actual motivation. On the one 20