public ArrayList<Short> getPrefTransportAccess() {
   ArrayList<Short> result = new ArrayList<Short>(householdPrefs.size());
   for (HouseholdPrefs prefs : householdPrefs) {
     result.add(prefs.getPrefTransportAccess());
   }
   return result;
 }
 public ArrayList<Short> getPrefSocialPrestige() {
   ArrayList<Short> result = new ArrayList<Short>(householdPrefs.size());
   for (HouseholdPrefs prefs : householdPrefs) {
     result.add(prefs.getPrefSocialPrestige());
   }
   return result;
 }
 public HouseholdPrefs lookupHouseholdTypePrefs(HouseholdType householdType) {
   HouseholdPrefs lookupHouseholdPrefs = new HouseholdPrefs();
   lookupHouseholdPrefs.setHouseholdTypeId(householdType.getId());
   int posHHType = Collections.binarySearch(householdPrefs, lookupHouseholdPrefs);
   assert posHHType >= 0
       : "No household preference data found for hh type " + householdType.toString();
   return householdPrefs.get(posHHType);
 }