Calculating Stiffness from Plate Load Test

[matest]

This may be one for the UK/Europeans . Can anyone explain which would be the preferred method of calculating the stiffness modulus from a plate load test
We normally use the formula given in HD25/94, E= 17.6(CBR)^0.64.
However, recently requested to calculate stiffness using Eurocode 7, Part 2, Annex K

 

[EireChch]

They second one as this considers poisson ratio