Calculating Delta Values: Paired t Test

[lamlam1]

Using paired t test, how should I pair these results?
To calculate the delta values, should I use: downstream - upstream for both sep and apr ?
or upstream (sep) - upstream (apr) and downstream (sep) - downstream (apr) ?

Thanks

 

[Dale]

What is the quantity that you want to test and which pairing gives you that quantity?

 

[WWGD]

How do you get a net pollution value? Is there a typo on increasing pollution? Shouldn't it be lowering pollution?

 

[BWV]

View attachment 240043

Using paired t test, how should I pair these results?
To calculate the delta values, should I use: downstream - upstream for both sep and apr ?
or upstream (sep) - upstream (apr) and downstream (sep) - downstream (apr) ?

Thanks

Only the delta for the same day makes sense as the concern is an upper limit of 4 mg/L increase. Not sure why comparing April and Sep as two populations is relevant, seems to me a one tailed t-test on the delta with a null hypothesis that the mean of the delta >4 would be the relevant test