This paper argues that the duration between successive children affects child survival (the sibling competition effect) while child survival too affects the duration between successive births (the child replacement effect). This inter-relationship is modelled in terms of a correlated...

Immigrants who arrived in the U.S. before the Civil War were less likely to reside in locations with high immigrant concentrations as their time in the U.S. increased. This is contrary to the experience of recent immigrants who show no decrease in concentration after arrival. The reduced...