def _inc_categories(inc_entry, inc_exit):
    """Returns an income category for given income-at-entry and income-at-exit.
    """
    if inc_exit > inc_entry:
        return 'Increased'
    elif inc_exit < inc_entry and inc_exit != -1:
        return 'Decreased'
    elif inc_exit == inc_entry == -1:
        return 'NO DATA'
    else:
        return 'No Change'