I have been asked to find the means and standard deviation for each of the groups below and collate the means and SD into a new table from which I can create graphs. Calculating the mean of the results in each time interval is quite easy but Im not sure if I am supposed to combine the standard deviation from each interval for each group.

Thanks in advance

Melatonin levels (pg/ml) Start Sampling time (mins) Bedtime Subject Light Treatment 0 20 40 60 80 100 120 Subject Light Treatment DIM- no device 1.0 4.0 8.0 12.0 18.0 DIM- no devic 33.8 37.0 0.8 3.2 21 6.4 DIM- with device 9.6 17.6 1.0 26.8 2.0 4.0 36.8 6.0 A W N H 10.0 14.0 DIM- no device 20.0 0.6 2.6 22 5.1 7.7 DIM- with device 19.4 0.3 33.0 0.3 39.0 6.0 15.0 23 19.5 23.0 DIM- no device 0.5 2.3 4.1 6.1 DIM- with device 28.0 0.5 15.2 0.6 25.7 29.0 1.8 3.4 6.2 1.O 24 4.4 DIM- no device 16.7 3.0 6.5 DIM- with device 11.5 17.5 0.6 0.4 29.1 42.5 5.3 13.3 17.2 21.0 26.4 DIM- no device 0.8 2.9 25 7.1 DIM- with device 9.2 1.0 18.0 27. 1.8 3.4 3.6 DIM- no device 41.0 4.7 0.5 26 6. 6 8.0 DIM- with device 12.8 4.0 14.0 24.9 0.8 0.5 28.0 1.5 3.8 6.8 DIM- no device 36.9 4.9 11.3 0.4 3.2 27 6.4 DIM- with device 11.2 0.6 18.3 36.5 2.0 o device 40.0 3.2 8.0 2.6 28 10.4 0.3 DIM- with device 14.6 0.5 18.9 5.1 9.0 16.3 0.3 39.0 1.0 10 4.0 2.4 29 7.3 DIM- no device 44.0 5.2 0.3 4.1 7.2 DIM- with device 15.5 1.0 19.7 31.0 0.7 38.0 2.1 3.3 30 4.3 DIM- with device 6.0 0.6 16.0 0.6 5.8 11.5 15.0 20.9 32.0 11 BRIGHT- no device 2.0 1.0 2.0 4.0 8.0 12 12.0 BRIGHT- no device 15.0 1.0 0.9 31 1.8 BRIGHT- with device 4.5 7.7 2.0 11.5 1.0 2.0 6.0 13 14.9 8.0 11.0 BRIGHT- no device 12.0 0.8 2. 1 32 4.2 BRIGHT- with device 1.2 0.7 0.9 1.2 2.0 14 10.5 17.9 BRIGHT- no device 11.1 14.4 4.3 0.3 33 3.6 BRIGHT- with device 4.9 0.6 0.6 6. 1 1.0 0.5 2.9 4.0 15 9.2 11.9 6.9 BRIGHT- no device 0.5 0.5 34 1.0 2.5 BRIGHT- with device 14.4 4.2 0.8 16.6 16 BRIGHT- no device 6.2 0.3 8.1 2.5 3.5 35 8.0 BRIGHT- with device 1.2 1.3 0.6 17.1 1.0 0.6 3.2 5.4 8.2 1.5 10.6 2.3 3.2 5.4 17 BRIGHT- no device 11.2 .3 12.9 1.0 36 1.9 BRIGHT- with device 4.8 0.5 8.1 0.6 BT 12. 1 BRIGHT- no device 15.7 1.0 4.3 7.3 13.4 0.6 37 15.4 1.3 2.6 BRIGHT- with device 6.5 1.0 0.6 3.6 5.0 10.9 19 11.1 16.6 BRIGHT- no device 21.5 38 18.0 17.6 0.4 1.7 3.4 BRIGHT- with device 8.5 0.6 14.5 0.1 20.1 2.2 22.0 3.0 5.1 20 30 10.7 BRIGHT- no device 0.6 1.0 2.0 5.0 BRIGHT- with device 12. 0.3 8.5 12.8 0.6 16.6 0.7 2.8 4.8 40 BRIGHT- with device 10.0 0.6 11.5 0.4 1.9 2.7 3.5 7.4 8.5 Start Sampling time (mins) Bedtime 0 20 40 60 80 100 Dim/No 0. 6 120 3.0 6.1 9.7 18.1 31.0 38.4 Bright/No 0.8 1.0 2.1 5.3 9.1 12.0 Dim/yes 15.1 0.7 0.9 3.4 7.2 9.6 12.6 Bright/yes 20.2 0.9 0.6 2.0 3.6 6.2 11.2 12.9