Numerous factors, increase the technical difficulty of standardization for the interpretation of PD-L1 expression in clinical settings, including the assays, antibodies and cut-offs used, the usage of archival or fresh tissue, the heterogeneity of synchronous and metachronous tumor specimens.
One disadvantage of using human roots as carriers is the difficulty of standardization of the size of the tubes.
Other important limitations of this type of assessment are difficulties of standardization, objectivity of scoring, and practicability for large groups of examinees.
4– 6 However, the validity of those markers remains controversial and their clinical application is limited due to their complexity, the difficulties of standardization, and the cost of measurement.
The difficulty is the lack of standardization and physiological validation of some of the most popular of these tests [ 23].
Just as challenging is the difficulty in the level of standardization required for large datasets and multicenter studies typical of large clinical trials [ 89].
For these blood feeding studies we chose an experimental design involving an artificial membrane feeding system (Parafilm M) with commercial human blood because of the difficulty in standardization and replication of parameters associated with the use of a mouse or a human arm, as it will be subjective to different individuals.
A problem in using natural herbal material is the difficulty in standardization of efficacy, which is partially due to factors such as differences in region of origin, harvest period, and cultivation time.
Self-reported measures are susceptible to biases (tendency to answer positively, give more socially acceptable answers, etc).. Another study limitation is the validity and reliability of knowledge assessments by questionnaires, which can be questioned because of the absence of standardization and difficulty when comparing them across studies[38], [39], [40].
At the same time, physicians find it difficult to acquire and use FHH due to time constraints, lack of standardization, and difficulty synthesizing into actionable prevention strategies [ 9- 12].
Biomarkers derived from exhaled condensates, induced sputums and bronchial fluids, while specific, have major shortcomings including lack of standardization and difficulty in procurement of samples that limit their application in large clinical trials or studies.
