I have below code from example of Angular UI Select:

<ui-select multiple ng-model="SelectedItem" style="width: 300px;">
    <ui-select-match placeholder="Select colors">{{$item}}</ui-select-match>
    <ui-select-choices repeat="color in availableColors">{{color}} Cool</ui-select-choices>
</ui-select>
<p>Selected: {{SelectedItem}}</p>

And nd-model didnt define any scope variable. <p> show only 'Selected: ' and in controller variable $scope.SelectedItem is undefined. The rest is working fine.