Title: Online labor markets
Description: The five essays of this dissertation explore the phenomenon of online labor markets through the lens of labor economics. The first essay provides an overview of these markets and discusses some of the economic questions they pose. The next essay discusses how the markets can be used as platforms for conducting field experiments and presents results from a number of replication studies.

The third essay presents a simple model of workers supplying labor to paid crowd-sourcing projects. It also introduces a novel method for estimating a worker's reservation wage -- the key parameter in the labor supply model. Experiments confirmed some of the key predictions of the model, though at least some subjects appear to be "target earners," contrary to the assumptions of the rational model. The strongest evidence for target earning is an observed preference for earning total amounts evenly divisible by 5, presumably because such amounts make good targets.

The fourth essay strives for more generality and explores the effects that peers can have in team production settings. In five field experiments, workers labeled photographs and evaluated their peers' performances at the same task. Evaluating high-output work made workers more productive, with stronger effects observed for higher-productivity workers. Even very explicit employer instructions were unable to stamp out these productivity peer effects. In their evaluations, workers punished workers who demonstrated low effort, but low output alone was not sufficient to trigger punishment. Willingness to punish was strongly correlated with a worker's own productivity, yet this relationship was experimentally mutable, with productivity-reducing treatments also reducing punishment.

The fifth essay focuses on the welfare implications of online work. Online labor markets are potentially controversial, in that workers often work for very low wages and can potentially be exploited by unscrupulous employers. At the same time, the markets have the potential to help workers in developing countries gain access to first world markets. I discuss these issues and present some survey evidence on worker attitudes towards employers.
Subjects: Labor market, Computer network resources, Labor economics, Labor, Quality control