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 distinct chance that sequence duplicates are NOT detected, just because they're peppered with sequencing errors in their 3' regions. Therefore the maximum number of 5' bases upon which the identity of two sequences is decided on, is restricted to 50nt.
- 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.
- 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.