The Effect of Homework on Exam Performance: Experimental Results from Principles of Economics

We assess the effect of the completion of online homework assignments on exam performance in “Principles of Economics” using a unique experimental method. For specific homework assignments we randomize students into two groups: those for whom the assignment is optional and those for whom it is required. This randomization, which affects incentives to complete the homework assignment for a particular topic, generates an instrument that helps identify the effect of homework completion on topic‐specific exam performance. Results of the instrumental variables analysis, as well as results of a variety of other analyses, indicate that the completion of the assigned homework is positively (if not always significantly) correlated with higher scores on the midterms but not on the final exam—indicating “decay” in the homework effect over the course of the semester.     

Population pressure, intensification of agriculture, and rural-urban migration

Low rates of labor absorption in rural areas with relatively low population density, such as Sub-Saharan Africa, are usually explained by poor natural conditions, mainly infertile tropical soil. I offer an explanation based on the extensive techniques of land use emplopyed in low density areas. I incorporate the intensity of land use as a parameter in a standard two-sector model to show that the rate of labor absorption (defined as the rate of natural population growth in the rural areas minus the rate of rural-urban migration) is positively correlated with the intensity of the technique of cultivation. An empirical section employs cross-section data from Iran to illustrate and confirm the relationships derived from the model.     

Mobility and the dynamics of poverty in Iran: Evidence from the 1992–1995 panel survey

In the last three decades, revolutionary Iran has experienced large shocks to its political and economic system with likely effects on poverty, inequality, and economic mobility. While poverty has declined, inequality has remained relatively high and stable over nearly four decades. In this paper, for the first time, we examine poverty and inequality in a dynamic context using a 4-year panel data, collected during 1992–1995. We show that short-term income mobility is relatively high, which helps mitigate persistent high inequality. We offer a range of estimates of transition probabilities, indicating that, for example, someone in the lowest (highest) quintile has between 25% and 50% chance of moving up (down) the income ladder. Focusing on the dynamics of poverty, we distinguish between short- and long-term poor and between chronic and transient poverty. Surprisingly, we find that chronic poverty is a more serious problem in urban than rural areas, while transient poverty is geographically more uniformly distributed. Finally, using Tobit and quantile regression, we examine the correlates of these two types of poverty. Both chronic and transient poverty are higher for households headed by women and by younger and less educated men. While minorities suffer more from transient poverty, they are less likely to be chronically poor. We discuss the implications of these findings for policy to alleviate chronic and transient poverty.