Abstract An instrumental variable can be used to test the causal null hypothesis that an exposure has no causal effect on the outcome, by assessing the association between the instrumental variable and the outcome. Under additional assumptions, an instrumental variable can be used to estimate...

It is widely believed that happiness is strongly correlated with wealth and income, but according to the happiness–income paradox, this is not always true. The paradox predicates that there is a strong positive correlation between income and happiness nationally, but the correlation is...

Nominal data currently lack a correlation coefficient, such as has already defined for real data. A measure is possible using the determinant, with the useful interpretation that the determinant gives the ratio between volumes. With M a m × n contingency table and n ≤ m the suggested measure...

Nominal data currently lack a correlation coefficient, such as has already defined for real data. A measure is possible using the determinant, with the useful interpretation that the determinant gives the ratio between volumes. With M a m × n contingency table and n ≤ m the suggested measure...

The Linder hypothesis states that countries of similar income per capita should trade more intensely with one another. This hypothesis has attracted substantial research over decades, but the empirical evidence has failed to provide consistent support for it. This paper shows that the reason for...