This paper draws parallels between the principal components analysis of factorless high‐dimensional nonstationary data and classical spurious regression. We show that a few such absorb nearly all variation. The corresponding scree plot suggests contain factors, which is corroborated by standard panel information criteria. Furthermore, Dickey–Fuller tests unit root hypothesis applied to estimate...

By facilitating early re-entry to the labor market after childbirth, public kindergarten might positively affect maternal human capital and outcomes: Are such effects long-lasting? Can we rely on between-individuals differences in quarter of birth identify them? I isolate interest from spurious associations through difference-in-difference, exploiting across-states over-time variation eligibili...

Ahstruet-It is shown that the outer-product method for programming the Hopfield model is shown, which can result in many spurious stable states-exponential in the number of vectors that we want to store-even in the case when the vectors are orthogonal.

A new approach to finite basis sets for the Dirac equation is developed. It does not involve spurious states and improves the convergence properties of basis-set calculations. Efficiency of the method is demonstrated for finite basis sets constructed from B splines by calculating the one-loop self-energy correction for a hydrogenlike ion.

Taking into account relativistic effects in quantum chemistry is crucial for accurate computations involving heavy atoms. Standard numerical methods can deal with the problem of variational collapse and the appearance of spurious roots only in special cases. The goal of this Letter is to provide a general and robust method to compute particle bound states of the Dirac equation.