NMR chemical shift prediction of allenes

The chemical shifts of alkenes can be estimated using substituent chemical shifts (SCS) for the geminal, cis and trans substituents.
The SCS values used for the calculations are taken from [1,2]. Both papers contain a much finer division of functional groups, e.g. different SCS values are given for conjugated and non-conjugated compounds. However, an exhaustive list would become unmanageable so only a subset is used here. In most cases the loss of accuracy is not great.
Since values for the ¹H increments of several groups are missing in [1] they are approximated using similar substituents.
Carboxylic acids and esters are approximated by increments for ketones/aldehydes
Alkynes are approximated with increments for cyano compounds (nitriles)

Literature

[1] "New parameters for prediction ¹H NMR chemical shifts of protons attached to carbon atoms"
Bürgin Schaller R, Arnold C, Pretsch E Anal. Chem. Acta 312 (1995) 95-105
[2] "Parameter set for the prediction of the ¹³C-NMR chemical shifts of sp²- and sp-hybridized carbon atoms in organic compounds"
Pretsch E, Fürst A, Robien W Anal. Chim. Acta 248 (1991) 415-428

R1= none Alkyl Alkene Phenyl Alkyne Ketone/Aldehyde Ester Carboxylic acid Cyano Chloro Bromo Iodo Ether Ester R2= none Alkyl Alkene Phenyl Alkyne Ketone/Aldehyde Ester Carboxylic acid Cyano Chloro Bromo Iodo Ether Ester R3= none Alkyl Alkene Phenyl Alkyne Ketone/Aldehyde Ester Carboxylic acid Cyano Chloro Bromo Iodo Ether Ester R4= none Alkyl Alkene Phenyl Alkyne Ketone/Aldehyde Ester Carboxylic acid Cyano Chloro Bromo Iodo Ether Ester