>> Quite right, Jim. Tell 'em to present the evidence.
>
>I would recommend to politely ask them to present the
>evidence, or, in the likely case that there might be no
>direct evidence at hand, to politely ask why they think
>it is either not possible or not necessary to collect this
>specific kind of evidence.

They would not be allowed collect this type of evidence.
Their funding would be cut off if they showed OWLS was
not constant.
No doubt they already have data that proves this but are
not game to reveal it to anyone.