The first part of this dissertation evaluates the effectiveness of food assistance by gathering evidence from developing countries and the United States. The first essay applies a multi-market model to three developing countries and simulate recent spikes in staple prices and food aid impacts. Results indicate that higher food prices would result in reduction in household real income and deterioration of household welfare. Food aid in the form of cash transfers targeted at low-income groups could improve household real income of the target group after world price shocks and, partially or completely, offset the negative impacts of higher food prices. The impact of cash transfer on untargeted groups is ambiguous. It is likely to be positive for households that are net producers of the commodities that have increased production and prices under cash transfer and the production surplus is sufficiently large. The second essay focuses on the Food Stamp Program (FSP), a cornerstone of food assistance safety net efforts in the U.S. to reduce household food insecurity, particularly among children. The essay examines the dynamic relationship between FSP participation and child food security using monthly measures. Empirical estimates using the Panel Study of Income Dynamics demonstrate that child food security declines in the months immediately prior to FSP entrance, but then partially recovers following program entrance. These dynamic FSP effects are masked when annual measures are employed.

The third paper of this dissertation studies the potential impacts of patient's widespread use of online health information. In particular, the essay employs a principal agent model and focuses on the quality of online health information. The model shows that when the quality of health information improves, since medical consultations become more efficient and less costly, a higher effort will be induced or contracted from the physician. Diagnosis becomes more accurate, because physicians will try exert more effort in diagnosing patients and patients will suffer less loss from their illnesses.