Jo Thori Lind

An implementation of Lind and Mehlum's (2010) Utest to test for the presence of a U shaped or inverted U shaped relationship between variables in (generalized) linear models. It also implements a test of upward/downward sloping relationships at the lower and upper boundary of the data range.

Adoption of low-carbon technology is key to mitigating climate change. A possible unwanted consequence of fast technological progress is that products get outdated before their technical lifetime is over. We investigate whether the market value of electric vehicles, characterized by rapid technological progress, declines faster over their lifetime than gasoline vehicles, which represent a mature technology. We use novel data from Norway, the market with the highest market shares for electric vehicles in the world. The data are from the largest web platform for secondhand vehicles over the period 2011–2021. Prices of electric vehicles decline faster than gasoline vehicles. This seems to be driven by the electric vehicles with below median driving range. We hypothesize that the large price drop is mainly due to the fast technological improvement of electric vehicles.

In social insurance systems that grant workers paid sick leave, physicians act as gatekeepers, supposedly granting sickness certificates to the sick and not to shirkers. Previous research has emphasized the physician's superior ability to judge patients' need of treatment and potential collusion with the patient vis‐á‐vis an insurer. What is less well understood is the role of patients' private information. We explore the case where patients have private information about the presence of nonverifiable symptoms. Anyone can then claim to experience such symptoms, reducing physicians' ability to distinguish between sick patients and shirkers. Doubting a patients' reported symptoms may prevent good medical treatment of the truly sick. We show that for all parameter values, the Bayesian Nash equilibrium is that some physicians trust all claims of nonverifiable symptoms, sicklisting shirkers as well as sick; for many values, every physician is trusting. In particular, if physician strategies are observable by patients, extremely strong gatekeeping preferences are required to make physicians mistrust. To limit unwarranted sicklisting, policies reducing the benefits of shirking for healthy workers may be better suited than attempts to convince physicians to be strict.

Rainfall is exogenous to human actions and hence popular as an exogenous source of variation. But it is also spatially correlated. This can generate spurious relationships between rainfall and other spatially correlated outcomes. As an illustration, rainfall on almost any day of the year has seemingly high predictive power of electoral turnout in Norwegian municipalities. In Monte Carlo analyses, I find that standard tests reject true null hypotheses in as much as 99% of cases. Standard approaches to estimating consistent standard errors do not solve the problem. Instead, I suggest controlling for spatial and spatiotemporal trends using multidimensional polynomials.

In four public-good game experiments, we study self-sorting as a means to facilitate cooperation in groups. When individuals can choose to join groups precommitted to charity, such groups sustain cooperation toward the group’s local public good. By eliciting subjects’ conditional contribution profiles, we find that subjects who prefer the charity groups have higher average conditional contribution levels but do not differ with respect to the slope of their profiles. The majority of subjects in both group types are conditional cooperators whose willingness to contribute is stimulated by generous group members but undermined by free-riders. Charity groups thus seem better able to sustain cooperation because they attract a greater number of more generous individuals, triggering generous responses by conditional cooperators.