The event-related potential (ERP) methodology has proven to be a robust approach to elucidate the time course and neural basis of cognitive process. Together with methods for data preprocessing, averaging across segments and across subjects are crucial analysis steps of the ERP methodology. These operations are possible with the transforms Average and Grand Average.
In Analyzer 2.2.0, the Average transform has been rewritten and ported to the .NET platform. Its user interface provides you with a new standard GUI control for segment selection, as well as a robust set of GUI validations to check the integrity of used parameters. Performance of numerical computations across segments is improved with the implementation of new algorithms. The Average – Grand Average workflow has been considerably optimized with the introduction of a new property to store the number of segments used for averaging in each channel. Also, the Operation Infos has been expanded to include detailed information about used parameters and channel specific information.
Grand Average consists of a rather complicated set of operations for selecting input history files, nodes and channels, which lead to the computation of valid output data. In Analyzer 2.2.0, Grand Average has been extensively rewritten to enhance the usability of the user interface and to improve vital aspects of this module. This includes the identification of the reference history file, the selection of valid nodes and channels, the logic of data aggregation when Individual Channel Mode option is on or off, the mathematical computations based on the number of segments/weights and the correct matching of input nodes, channels and units.
The new user interface is utterly improved by a standard GUI control for history file selection, which makes the selection process more flexible and effective. Both parameters in the GUI and data properties during calculations are submitted to a stricter validation, in order to guarantee the validity of Grand Average output data.
You will find a new structure of the Operation Infos, which includes a detailed report of the analysis steps. It addresses relevant questions such as: what’s my reference node? which nodes are included and excluded? how many segments contributed to the grand average calculation, in each channel? why is a particular node excluded?
Alongside this, the Operation Infos includes warnings on minor issues affecting the input data.