subtle, it may be reasonable to accept them, e.g. at least 3 different sets of criteria are commonly used to define Parkinson’s disease worldwide and their concordance is high. For most teams in the field, it is extremely difficult to go back and re-define cases and controls based on different criteria. Conversely, with stark differences in definitions, an effort at harmonization is essential. Exploratory analyses may be performed with different definitions and/or adjustments. However, picking the best results with particular definitions/adjustments post hoc may generate spuriously inflated signals of significance [17].
