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 22.

  
Figure 22: Statistical Parameter popup window.

1. The first step in calculating a statistical map is to populate the list (22-1). This is accomplished by first entering the (22-2) and times (22-3), followed by pressing the (22-4) button. The (22-13) and (22-14) buttons can be used for editing the currently selected period from the list.
2. There are four choices (22-5):
   • Mean
   • StdDev (Standard Deviation)
   • Min
   • Max

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

3. The (22-6) 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 option (22-7) 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 button (22-12) 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 (22-11). 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 option (22-8) can be selected. The AutoSave option will automatically save the parameters to the current file. The button (22-9) can be used to retrieve previously save parameters.
6. Having all the parameters and options set, pressing the button (22-10) invokes the calculation of the statistical map. See Section 9.1 for the details on how to display the map.