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Presidential candidates in the United States do not intentionally advertise in states without rigorous competition for electoral votes. However, in some areas of noncompetitive states, media markets overlap with battleground states, exposing these regions to political ads. These spillover advertisements allow us to examine the relationship between advertisements and individual campaign contributions, with data from the Wisconsin Advertising Project and the Federal Elections Commission. Using propensity‐score matching within uncontested states, we find that 2008 aggregate giving in zip codes exposed to political ads was approximately $6,100 (28.1% of mean contributions) more than in similar zip codes without advertisements.  相似文献   
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This article provides a comprehensive review of the literature on the nature and evolution of rural livelihood diversification in sub-Saharan Africa, and the situation regarding smallholders. It reveals mixed findings about the causes and consequences of livelihood diversification on rural smallholders adopting this strategy. A lot of evidence from the literature suggests that it is relatively better-off smallholders with sufficient assets who achieve successful livelihood diversification, mainly by exploiting opportunities and synergies between farm and nonfarm activities. Because of asset constraints, increase in incomes and wealth based on livelihood diversification has not yet benefitted the large majority of smallholders.  相似文献   
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Assessing self-harm through brief multiple choice items is simple and less invasive than more detailed methods of assessment. However, there is currently little validation for brief methods of self-harm assessment. This study evaluates the extent to which adolescents’ perceptions of self-harm agree with definitions in the literature, and what level of question detail produces optimal concordance rates. Two hundred and thirty-three (69% female) first year university students aged 17–21 completed a self-harm coding task; we created three levels of question detail and randomly allocated participants to three study groups: brief, low detail, and high detail. The present findings suggest that that adolescents’ perceptions of self-harm are generally concordant with a consensus definition of self-harm. Low level of detail in the question produced greatest accuracy in responses; adolescents who demonstrated adequate task understanding were able to correctly identify 94% of examples of self-harm behaviour and 86% of examples of behaviour that were not self-harm. We identified lower concordance rates for eating disordered behaviour and recreational petrol sniffing. This indicates that adolescents perceive these behaviours to be self-harm, in contrast to the reference definition we utilised. Overall, this study provides support for using a brief assessment of self-harm where minimal detail regarding self-harm behaviour is required.  相似文献   
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