 An overview of econometric methods used to study this problem were provided by Card (1999).The main journals that publish work in econometrics are "Econometrica", the "Journal of Econometrics", "The Review of Economics and Statistics", "Econometric Theory", the "Journal of Applied Econometrics", "Econometric Reviews", "The Econometrics Journal", "Applied Econometrics and International Development", and the "Journal of Business & Economic Statistics".Like other forms of statistical analysis, badly specified econometric models may show a spurious relationship where two variables are correlated but causally unrelated.