Some aspects of goal-oriented a posteriori error estimation are addressed in the context
of steady convection-diffusion equations. The difference between the exact and
approximate values of a linear target functional is expressed in terms of integrals
that depend on the solutions to the primal and dual problems. Gradient averaging
techniques are employed to separate the element residual and diffusive flux errors
without introducing jump terms. The dual solution is computed numerically and
interpolated using higher-order basis functions. A node-based approach to localization
of global errors in the quantities of interest is pursued. A possible violation of
Galerkin orthogonality is taken into account. Numerical experiments are performed
for centered and upwind-biased approximations of a 1D boundary value problem.