  This paper introduces measures for how each moment contributes to the
precision of parameter estimates in GMM settings. For example, one of the
measures asks what would happen to the variance of the parameter estimates if a
particular moment was dropped from the estimation. The measures are all easy to
compute. We illustrate the usefulness of the measures through two simple
examples as well as an application to a model of joint retirement planning of
couples. We estimate the model using the UK-BHPS, and we find evidence of
complementarities in leisure. Our sensitivity measures illustrate that the
estimate of the complementarity is primarily informed by the distribution of
differences in planned retirement dates. The estimated econometric model can be
interpreted as a bivariate ordered choice model that allows for simultaneity.
This makes the model potentially useful in other applications.
