Further Considerations of Underwriting Margins, Interest Rates, Stability, Stationarity Cointegration, and Time Trends

This article provides a philosophical discussion detailing the limitations of univariate analysis in the pre-testing step of data analysis. The case in point is the relationship between the property-liability aggregate underwriting margin and interest rates. Haley (1993) and Choi, Hardigree, and Thistle (2002) both found strong evidence indicating such a relationship exists. Since then assorted authors, relying extensively on univariate analysis, have questioned the cointegration conclusion. The paper uses a cointegration analysis of the property-liability aggregate underwriting margin and interest rates (1930–2000) to illustrate the discussion.