Duplicated sequences analysis
The duplicated sequences analysis identifies sequences that have been sequenced multiple times. In order to achieve reasonable performance, not all input sequences are analyzed. Instead a sequence-dictionary is used, whose entries are sampled evenly from input sequences. Please note that if you select multiple sequence lists as an input, they will all be considered one data set for this analysis (batching can be used to generate separate reports for an individual sequence list). As soon as a sequence makes it into the dictionary (which is a random process), it is tracked for duplicates until all sequences have been examined. The dictionary size is 250 000 sequences.Because all current sequencing techniques tend to report fading quality scores for the 3' ends of sequences, there is a risk that duplicates are NOT detected, just because of sequencing errors near their 3' ends. Therefore, the identity of two sequences is calculated using only the first 50nt from the 5' end.
- Sequence duplication levels
- This results in a table correlating duplication counts with the number of sequences that featured that duplicate-count. For example, if the dictionary contains 10 sequences and each sequence was seen exactly once, then the table will contain only one row displaying: duplication-count=1 and sequence-count=10. Note: due to space restrictions the corresponding bar-plot shows only bars for duplication-counts of x=[0-100]. Bar-heights of duplication-counts >100 are accumulated at x=100, such that a significantly elevated bar-height at x=100 is a normal observation. Please refer to the table-report for a full list of individual duplication-counts.
- Duplicated sequences
- This results in a list of actual sequences most prevalently observed. The list contains a maximum of 25 (most frequently observed) sequences and is only present in the supplementary report.