There is a list of the most common reasons cited by reviewers for an applications lack of success:
Lack of significance to the scientific issue being addressed.
Lack of original or new ideas.
Proposal of an unrealistically large amount of work (i.e., an overambitious research plan).
Scientific rationale not valid.
Project too diffuse or superficial or lacks focus.
Proposed project a fishing expedition lacking solid scientific basis (i.e., no basic scientific question being addressed).
Studies based on a shaky hypothesis or on shaky data, or alternative hypotheses not considered.
Proposed experiments simply descriptive and do not test a specific hypothesis.
The proposal is technology driven rather than hypothesis driven (i.e., a method in search of a problem).
Rationale for experiments not provided (why important, or how relevant to the hypothesis).
Direction or sense of priority not clearly defined, i.e., the experiments do not follow from one another, and lack a clear starting or finishing point.
Lack of alternative methodological approaches in case the primary approach does not work out.
Insufficient methodological detail to convince reviewers the investigator knows what he or she is doing (no recognition of potential problems and pitfalls).
Most experiments depend on success of an initial proposed experiment (so all remaining experiments may be worthless if the first is not successful).
The proposed model system is not appropriate to address the proposed questions (i.e., proposing to study T-cell gene expression in a B-cell line).
The proposed experiments do not include all relevant controls.
Proposal innovative but lacking enough preliminary data.
