correlation between vote buying and health services. The weaker correlation of health services with these other measures of clientelism, compared to the stronger correlation with the vote buying measures, is attributable to two factors. One, these measures of economic power of the mayor’s family directly captures economic characteristics of a municipality that could be correlated with health investments (both public and private) outside of the channel of clientelism. Two, there is no available data to examine whether mayoral economic power is indeed associated with clientelism; it is therefore a more noisy measure of clientelist practices than the direct measure of vote buying.

The degree to which politicians face competition in accessing office has also been argued to explain the use of vote buying strategies, particularly in interaction with poverty; where both poverty and competitive pressures are high, vote buying may be more likely to be the selected strategy (Weitz-Shapiro, 2012). Measuring variation in political competition across municipalities in the Philippines is tricky. Carizo (2010) provides a detailed qualitative description of competition in the Isabela municipalities studied here, showing: one, that observed variables such as the number of candidates that compete for mayoral office may be endogenous to actual performance of incumbent politicians (well performing incumbents can stand unopposed); two, that local political clans can make deals with each other to alternate in office, such that even when there is an underlying competitive threat, it may not be reflected in observed variables; three, that margins of victory or vote shares may be fraudulently derived, or directly reflecting vote buying outcomes (rather than measuring underlying differences in competitive pressure).

Given these considerations, the most reliable measure of variation in local competitive pressures, in this context, may be the existence and degree of entrenchment of political clans. Based on the information compiled by the Institute for Popular Democracy (IPD) in the Philippines, using raw electoral data from the election commission in the Philippines, about 57 percent (17 out of the sample of 30 municipalities) of municipalities have one or more political clans holding or competing for public office. A scrutiny of the names of mayors who have held office in these municipalities since 1998 also reveals that in one-third of the municipalities one political clan has been entrenched in the position of mayor, alternating between family members when any one candidate faces a term limit.<sup>25</sup> Including fixed effects for the congressional districts to which the municipalities belong may also capture the degree to which electoral competition matters for explaining variation in vote buying. There are four congressional districts in Isabela, of which three are described as being dominated by particular political clans (Carizo, 2010). The fourth district, in contrast to the other three, is described as experiencing intense rivalry among warring clans. There is evidence of greater vote buying in those municipalities that are located in the 4<sup>th</sup> congressional district, which is characterized by more intense political rivalry between clans. However, municipalities in the 4<sup>th</sup> district do not appear to be different in vote buying experience from those in the 1<sup>st</sup> district where a single clan has been known to dominate. The size of the difference in vote buying in municipalities in the 2<sup>nd</sup> and 3<sup>rd</sup> districts (each dominated by a different political clan)

> 25 The Philippines prohibits incumbent mayors in their third term in office from running in elections for a fourth consecutive term. However, candidates can return to contest in a subsequent election, after sitting-out the fourth term. Mayoral elections are scheduled every 3 years.

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