Conditions under which index models are useful: Reply to Bio-index Commentaries

This paper summarizes the key conditions under which the index method is valuable for forecasting and describes the procedures one should use when developing index models. The paper also addresses the specific concern of selecting inferior candidates when using the bio-index as a nomination helper. Political decision-makers should not use the bio-index as a stand-alone method but should combine forecasts from a variety of different methods that draw upon different information. The commentators raise important issues that Armstrong and Graefe (2011) do not address. Voss (2011) argues that (1) many of the variables used in the bio-index might have no causal relationship with the election outcome and (2) the bio-index might yield a poor selection of candidates, as it does not consider candidates ’ personalities, their stands on political issues, or their likely performance. More generally, Cote (2011) has concerns with the suitability of the index method for other problems such as business decision-making. The commentaries help to explain the conditions under which the bio-index i