$scope.$watch('pageOneForm.$valid', function(validity) {
      ModelData.actualPageCompleted = validity;
})

<div ng-Controller="PageTwo" ng-show='data.actualPage == 2'>
    <form  name="pageTwoForm">
        <h3>General Information > Knowledge About </h3>
        <div>
        <b>User</b>
        <div ng-repeat="option in userOptions">
            <input type="radio" name="userGroups" ng-model="data.knowledgeAboutUser" ng-value="option.id" id="{{option.id}}" required>{{option.text}}
        </div>


        <div ng-repeat="option in targetGroupUserOptions">
            <input type="radio" name = "targetUserGroup" ng-model="data.knowledgeAboutTargetGroup" ng-value="option.id" id="{{option.id}}" required>{{option.text}}
        </div>
    </div>
</form>

$scope.$watch('pageTwoForm.$valid', function(validity) {
      ModelData.actualPageCompleted = validity;
})

$scope.forceDigest = function(){
        setTimeout(function(){ $rootScope.$$phase || $rootScope.$apply(); });
    };

<h3 ng-show="false">{{data.knowledgeAboutTargetGroup}}</h3>
    <h3 ng-show="false">{{data.knowledgeAboutUser}}</h3>