It is purely anecdotal evidence and unscientific.

"Without a living Wwafida, or a Galeayan in the process of senescence, the evidence is purely anecdotal."

These claims were purely anecdotal, and none had been verified by independent clinical trials.

(I know this is not the case everywhere and things may have changed, but this is purely anecdotal).

And I agree with you, and it's purely anecdotal, but I have been much healthier since I took it.

Purely anecdotal of course - but in those days "firsts" were regarded by lecturers and students as exceptional and really really difficult to get!

Personal preferences for this or that novel, although clearly visible in the analysis, will be of a purely anecdotal significance.

Many were purely anecdotal accounts, made up of hearsay on top of hearsay.

The evidence is purely anecdotal.

Purely anecdotal but this sort of discussion makes me think of two former academic colleagues.