For a young boy without a history of FAP, trauma, or surgical procedures, it is difficult to define an intra-abdominal tumor near the stomach as a desmoid tumor.
If existing apheresis medicine service capacity can absorb those procedures, it is difficult to argue that the hospital has incurred a new "cost".
However, based on the diversity of sheared fragments and complicated PCR procedures, it is difficult to estimate the accurate amplification rate for each locus.
Retrospectively, it is also difficult to determine the further diagnostic follow-up based on the extraintestinal MR-E findings: often patients undergo several diagnostic procedures and it is difficult to determine, if new diagnostic procedures were ordered based on the MR-E findings or other clinical decisions.
Surgeons vary in their preference and skill for different procedures and it is difficult to standardise these.
The LRW procedure involves a nonlinear operation, thus it is difficult to analyze its properties on a general graph model.
In the Lasso procedure, it is difficult - if not impossible - to enforce a preference for speech atoms over noise atoms.
While one cannot completely rule out that the observed changes are arising from technical differences between sites in sampling procedures for instance, it is difficult to understand how these site effects could specifically impact only on a subset of correlated analytes.
When the consensus procedure is ill defined, it is difficult to ascertain which aspects might have influenced the outcome or how reliably expert opinion and stakeholders' preferences were incorporated (Grol et al, 2003; Raine et al, 2005).
Because of differences in antibodies, staining and tissue processing procedures in different studies, it is difficult to compare findings between studies directly.
