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- Your set has no coherent functional signal. This is a biological phenomenon where GREAT identifies that your set has no shared signal. To see the most enriched terms, regardless of statistical significance, switch to "Full View" and lower or remove the "Binomial Fold Enrichment" filter.
- Your set is too small. If your input set consists of a very small number of regions (< 10), it is difficult to achieve statistical significance. While it is difficult for GREAT to identify shared signals in a small set, you can change to "Full View" to see the most enriched terms in your small set, regardless of whether the term enrichment achieves statistical significance.
- Your set is too large. Large data sets can cause a large fraction of all genes to be selected via the regulatory domain association rules. This often results in saturation of the hypergeometric test over genes such that no hypergeometric test results are significant. See Handling Large Datasets for tips on how best to run GREAT on large data sets.
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