In many cases assignment to a treatment may affect concomitant variables. I show how a concomitant variable can be used to corroborate evidence from an observational study. In the observational study two types of training programs are compared. One program is part of regular Swedish labor market...

The issue considered in this study is whether objective, official reports on disability status are reliable. While there is a rather large literature on the reliability of self-reported disability, evidence regarding objective data is scant. It seems to be a widely held view among researchers...

The paper exploits a unique social experiment carried out in 1988 in Sweden to identify the effect of monitoring on sickness absence. The treatment consists of postponing the first formal point of monitoring during a sickness absence spell, a requirement for a doctor’s certificate, from day...

We perform inference on the effect of a treatment on survival times in studies where the treatment assignment is not randomized and the assignment time is not known in advance. We estimate survival functions on a treated and a control group which are made comparable through matching on observed...

We utilize a large-scale randomized social experiment to identify how coworkers affect each other's effort as measured by work absence. The experiment altered the work absence incentives for half of all employees living in Göteborg, Sweden. Using administrative data we are able to recover the...

Abadie and Imbens (2008, Econometrica) showed that classical bootstrap schemes fail to provide correct inference for K-nearest neighbour (KNN) matching estimators of average causal effects. This is an interesting result showing that bootstrap should not be applied without theoretical...

During the last decade several empirical studies have stressed the importance of norms and social interactions for explaining sickness absence behavior. In this context public discussions about the intentions of the insurance, and of the rights and duties of the receivers, may be important for...

We test if social work norms are important for work absence due to self-perceived sick-ness. To this end, we use a randomized social experiment designed to estimate the effect of monitoring on work absence. The treated were exposed to less monitoring of their eligibility to use sickness...

To study effects of out-of-school learning we use data on boarding home pupils who attended elementary public schools in the 1940's. The out-of-school environment at the boarding homes could be considered being more learner friendly than the home environment on average: the pupils at the...

We evaluate an immigrant workplace introduction program aimed at helping individuals considered employable but at the same time expected to experience substantial difficulties in finding work. Using supported employment methods, the SIN program may influence outcomes through several channels. We...