# Are pairwise combinations of an additive quantity valid ‘samples’?

I have a subject that is measured for a continuous quantity V at multiple subsequent points in time (t1, t2, t3 etc). At each measurement time, the quantity V is essentially ‘reset’ back to 0 and V is essentially ‘additive’ in nature, can I create a set of ‘pseudo-samples’ based on all the pairwise combinations of each measurement time? i.e. if the measurements at t1 and t2 were missed for some reason, the value of V at t3 would theoretically be equivalent to V1 + V2. In matrix form, my samples would exist along the sub-diagonal, so my questions is can all of the values in the upper triangle matrix be used as additional ‘samples’? The intent for these data will be to build a predictive model of the quantity V so I was thinking that adding these values in might be beneficial? The image below (attempts) to illustrate my question, Measurements are collected at V1, V2 etc. are the yellow ? valid samples as well (V1 + V2 + V3, V1 + V2, V2 + V3) Thanks