Notes concerning Local Selection Mode

• All the data views (plots and data tables) attached to a common DataObject operate in the same selection mode (either global or local).
• There is a limit of 31 selector views per DataObject. There is no limit to the number of observer views.
• It is usually the case that one wants multiple selector views but only one observer view. Thus, it is quickest to use the plot that is to become the observer view to effect the switch to local selection mode because it enables you to configure the observer view at the same time you are switching to local selection mode.
• When analyzing data in local selection mode in a situation where the observer view is a plot that displays observation markers, it is often useful to configure the plot to show only the selected observations. To accomplish this, perform the following steps:
1. In the plot window, right-click in the Plot Area to display the popup context menu and then click Plot Area Properties.
   -or-
   Press SHIFT+F10 to display the popup context menu for the Plot Area and then click Plot Area Properties.

   IML Studio will display the Plot Area Properties dialog box.

2. In the Plot Area Properties dialog box, click the Observations tab.
3. Select Show only selected observations.
4. If you would also like for the selected observations to be labeled, select Label all observations and then select a label variable in the Label observations by list.

   Labels are only displayed for visible observations.

5. Click OK.

• Conceptually, the intersection scheme is a boolean logic expression of the form

  Selector1Selections AND Selector2Selections AND Selector3Selections ...

  The selection state of each selector view represents that view's contribution to the overall expression. The subexpression contributed by each selector view is usually of the form

  low_cutoff <= var <= high_cutoff

  for single-variable plots, or

  (low_X_cutoff <= Xvar <= high_X_cutoff) AND (low_Y_cutoff <= Yvar <= high_Y_cutoff)

  for two-variable plots. By using extended selection, it is possible for a selector view to contribute a subexpression containing an OR operator. Extended selection is the technique of extending a selection by holding down the SHIFT or CTRL key while selecting observations with the mouse.

  Consider the situation of a histogram selector view that displays student test scores. Normally, the selection state of the histogram would contribute a subexpression of the form

  low_cutoff <= score <= high_cutoff

  By using extended selection, however, it would be possible to select the bars corresponding to high scoring students and to low scoring students at the same time. This would result in the histogram contributing a subexpression of the form

  (score <= low_cutoff) OR (score >= high_cutoff)