Although mortality at advanced ages can be well fit by heterogeneity models, population heterogeneity remains theoretical, lacking much direct evidence to support the existence of unobserved heterogeneity.
1993 (232), even makes the radical claim that the theoretical virtues lack real content and play no more than a rhetorical role in science.
For both theoretical and (lack of) data-related reasons, fertility choices have been investigated mostly from an individual perspective.
Moreover, scientific knowledge often lacks relevance and usability for practitioners as it often focuses heavily on theoretical issues, lacks local examples, and fails to address real world problems.
Figure 3a also shows that a theoretical prediction lacking the contribution from photon-assisted tunnelling is in clear disagreement with the measurements.
The planning in the design phase is rather theoretical and lacks practical input, which could be provided by the contractor.
Experimental realization has however not kept pace with theoretical considerations, lacking efficient methods for the deposition of a thick film porous layer within a microbore capillary.
Although inclined towards writing "in a theoretical way", his lack of a literary grounding saw him falter.
