y            < 0.001  
          Once every hour    38 (32.8)    26 (10.3)  
          Every 2-3 hourly    30 (25.9)    50 (19.7)  
          Every 3-4 hourly    21 (18.1)    77 (30.4)  
          Less than that    37 (31.9)    100 (39.5)  
     Appropriate duration ensured