STRAF is a browser-based application that allows to perform forensics and population genetics analysis of STR data.
STRAF accepts tab delimited txt-tables of different content. The first column needs to contain the sample ID and the second the population ID (if several populations are studied). Most convenient for the analysis of forensically relevant autosomal STR data, STRAF accepts point alleles. Allele data for haploid samples is entered with one column per locus and for diploid data with two columns per locus. Missing data (e.g. null alleles) must be indicated with a “0”. An example of a diploid input file is provided in the supplementary data for this article. This format is designed to facilitate the input file generation from a typical Excel file (Save as > Text (Tab-delimited) (*.txt)). Examples of diploid and haploid input files can be downloaded using the following links:
Download STRAF diploid example file. Download STRAF haploid example file.It is also possible to use a format similar to the Genepop input format, with both alleles (for diploid data) coded in one column, either with 2 or 3 digits. Note that in order to use this format, no point alleles should be present in the data set. Here is an example input file:
Download Genepop-like example file.STRAF computes standard forensics parameters. Some standard population genetics analysis can be achieved if the samples are assigned to different populations. STRAF generates downloadable tables, and plots can be personnalized (using the Graphical parameters section on the left panel) before saving them. Details about the methods can be found in Gouy & Zieger (2017).
Use the left panel to choose and upload your file. If no error appear once the file is uploaded, three tabs appear on the right page: Data, Forensics analysis and Population genetics analysis.
On the Data tab, three checkboxes allow to 1. display the dataset, 2. plot the distribution of alleles frequencies per locus, and 3. display a table of allele frequencies. This table is formatted as in most forensics data reports (rows = alleles; columns = loci). You can download this table as a TSV file readable in Excel by clicking the Download button.
On the Forensics analysis tab, you can compute all the standard forensics parameters for your dataset. You can download the table and plot the results.
On the Population genetics analysis tab, standard population genetics statistics can be computed (F-statistics, HWE, LD, ...). A PCA can also be performed to study population structure or discover outliers.
Please cite STRAF if you use it for your project using the following reference:
Gouy, A., & Zieger, M. (2017). STRAF - A convenient online tool for STR data evaluation in forensic genetics. Forensic Science International: Genetics, 30, 148-151.
STRAF is a browser-based application that allows to perform forensics and population genetics analysis of STR data.
Any file uploaded to STRAF is deleted when the session is closed. No data is retained on the server.
The STRAF software as a whole is distributed under GPL-3 (GNU GENERAL PUBLIC LICENSE version 3). This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License version 3 (GPL-3) as published by the Free Software Foundation.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details (https://www.gnu.org/licenses/gpl.txt).
STRAF benefited of the comments of Martin Zieger, Peter Vallone, Peter de Knijff, Guanglin He and Martin Bodner.