Statistical

A Statistical map gives a standard statistic of the functional time course over a specified set of periods. The Statistical parameter popup window is shown in Figure 25.

  
Figure 25: Statistical Parameter popup window.

1. The first step in calculating a statistical map is to populate the Periods list (25-1). This is accomplished by first entering the Start(25-2) and End times (25-3), followed by pressing the Add (25-4) button. The Change (25-13) and Delete (25-14) buttons can be used for editing the currently selected period from the list.
2. There are four Map Type choices (25-5):
   • Mean
   • StdDev (Standard Deviation)
   • Min
   • Max

   The resulting map reflects the statistical value calculated over all the points within the specified periods.

3. The PZM (25-6) option stands for ``Period Zero Mean,'' and is useful when there exists a baseline drift in the time course. With the PZMV option, the period mean is subtracted from each point within its respective period prior to the calculation of the statistic.
4. Next, the Mask option (25-7) can be selected to speed up the analysis by limiting which pixels are evaluated. When the mask option is selected only those pixel locations with non-zero values in the currently loaded mask are evaluated.
5. Prior to calculating the statistical map, the parameters must be saved to a file. Pressing the Save button (25-12) will popup the file browser (See Section 5). After the parameters are saved, the name of the file will appear in the lower left hand corner (25-11). When any parameter is changed the file name disappears since it is no longer consistent with the contents of the file. However, while a file name is displayed, the AutoSave option (25-8) can be selected. The AutoSave option will automatically save the parameters to the current file. The Load button (25-9) can be used to retrieve previously save parameters.
6. Having all the parameters and options set, pressing the Do Map Calc button (25-10) invokes the calculation of the statistical map. See Section 9.1 for the details on how to display the map.