Participants completed 6 saliva samples throughout the day to capture changes in cortisol and melatonin from waking until just before sleep. To achieve total AUC, 5 trapezoids between samples 1-6 were calculated.

Timepoints:

1st sample: upon waking

2nd sample: 30min following 1st sample

3rd sample: 3hours following 2nd sample

4th sample: 6hours following 3rd sample

5th sample: 30min before bedtime

6th sample: just before falling asleep

When calculating AUC the formula of the trapezoid (which would be 5 trapezoids in this case)

area = ((a+b/2)*h); where a&b are hormone values & h is the distance along the x axis = time diff between samples

trapezoid 1: (1st sample cortisol value + 2nd sample cortisol value/2)*h

My Q is.. if participants missed a sample at any point (where in my case this was mostly the 3rd / 4th sample) this could miss out 2 x AUC trapezoids in the total AUC and thus affect the final AUC cortisol value...would this matter? and is there a point in the curve where it is critical to include where the slope shape can't be estimated?

Any thoughts would be greatly appreciated :D

Thankyou!