Estimating System Parameters
Because a system parameters set is unique for your lab’s SOPs, no sets are pre-loaded in the MaSTR database. Instead, you must estimate the system parameters (also referred to as generating a system parameters set) for your lab’s SOPs. This estimation requires, at a minimum, the following files:
• The Panel file that details the panel that was used to analyze the single source validation samples.
• A System Parameters Single Source Profile file.
• A System Parameters Single Source Signal file.
Optionally, when estimating system parameters, you can also upload the following files:
• A LUS data file.
• A user-defined Stutter file.
Finally, if you are concerned that you might be required to recreate every iteration of the system parameters estimation for a court case, then you can also elect to generate a random seed. You can then set up another system parameters estimation with the identical input (panel, signal file, profile file, and so on), specify this seed and MaSTR repeats the original system parameter estimation in its entirety, step by step, exactly as it was carried out the first time.
MaSTR estimates system parameters in six distinct steps, or tasks. All six steps must be successfully completed to generate a systems parameters set. The table below details these steps.
Step # | Step Name | Step Description |
|---|
1 | Download Inputs | Download the panel used to amplify the samples, the required Single Source Signal file, the required Single Source Profile file, and if applicable, the optional LUS data file and/or the optional user-defined Stutter file. |
2 | Validate | Validate that the panel that you are using for the DNA analysis contains all the alleles that are present in your samples. |
3 | Estimate Stutter | Estimate stutter for all markers in the panel. |
4 | Estimate System Parameters | Estimate the expected parameters for variance (which accounts for allele drop-out) and peak height variations when analyzing samples according to your lab’s SOPs. |
5 | Plot Stutter | Automatically graph and display the stutter ratio for each allele in every marker. |
6 | Generate Variance Plot | Automatically graph and display the variance for each allele in every marker. |
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