Now showing 1 - 4 of 4
  • Publication
    Anchoring bias and covariate nonresponse
    (University College Dublin. Institute for the Study of Social Change (Geary Institute), 2003-05)
    Non-random item nonresponse makes identification of parameters problematic. Such nonresponse can occur with respect to both dependent and conditioning variables. A method often used to reduce nonresponse is that of adding unfolding brackets as follow up to open-ended questions. With these, initial non-respondents can provide additional (incomplete) information on the missing value. However, recent studies suggest that responses to unfolding brackets can lead to a type of bias as a result of 'the anchoring effect'. In this paper, bounding intervals of the type as presented in Horowitz and Manski (1998) are extended to incorporate information provided by bracket respondents while allowing for different types of anchoring, and, therefore,accounting for significant nonresponse in the conditioning set. The theoretical framework is illustrated with empirical evidence based on the 1996 wave of the Health and Retirement Study.
  • Publication
    Nonparametric bounds in the presence of item nonresponse, unfolding brackets, and anchoring
    (University College Dublin. Institute for the Study of Social Change (Geary Institute), 2001-09) ; ;
    Household surveys often suffer from nonresponse on variables such as income, savings or wealth. Recent work by Manski shows how bounds on conditional quantiles of the variable of interest can be derived, allowing for any type of nonrandom item nonresponse. The width between these bounds can be reduced using follow up questions in the form of unfolding brackets for initial item nonrespondents. Recent evidence, however, suggests that such a design is vulnerable to anchoring effects. In this paper Manski’s bounds are extended to incorporate the information provided by the bracket respondents allowing for different forms of anchoring. The new bounds are applied to earnings in the 1996 wave of the Health and Retirement Survey. The results show that the categorical questions can be useful to increase precision of the bounds, even if anchoring is allowed for.
  • Publication
    Selection bias and measures of inequality
    (University College Dublin. Institute for the Study of Social Change, 2002-02) ; ;
    Variables typically used to measure inequality (e.g., wage earnings, household income or expenditure), are often plagued by nonrandom item nonresponse. Ignoring non-respondents or making (often untestable) assumptions on the nonresponse sub-population can lead to selection bias on estimates of inequality. This paper draws on the approach by Manski (1989,1994) to derive bounding intervals on both the Gini coefficient and the Inter-Quartile range. Both sets of bounds provide alternative measures of inequality which allow for any type of selective nonresponse, while making no assumptions on the behaviour of non-respondents. The theory is illustrated measuring earnings inequality (over time and between samples) for post-unification Germany over the nineties.
  • Publication
    The effect of disability on labour market outcomes in Germany : evidence from matching
    (University College Dublin. Institute for the Study of Social Change (Geary Institute), 2003-02) ;
    If labour market policies aimed at people with disabilities are effective, we should observe no significant difference in labour market outcomes between disable and non-disable individuals. This paper examines the impact of disability status on labour market outcomes using matching methods associated with treatment effect techniques for program evaluation. Such techniques avoid model misspecification and account for the common support problem, thus improving the identification strategy of alternative techniques that also select on observables. Using several waves from the German Socio-Economic Panel (GSOEP, 1994-2000) we estimate the impact of disability on both labour market participation and labour earnings. We find no significant difference in either of these two measures of labour market outcomes between disable and non-disable. Due to the construction of the treated and comparison groups, our results imply that (in Germany) disability labour market policies are effective at achieving their aim.