NMR chemical shift prediction of alkenes

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 fluoro, nitro and sulfoxides were not given in [1] they were estimated using published NMR data.

Literature

[1] "Estimation of the chemical shifts of olefinic protons using additive increments - II The compilation of additive increments for 43 functional groups"
Mater UE, Pascual C, Pretsch E, Pross A, Simon W, Sternhell S Tetrahedron 25 (1969) 691-697
[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 Ketone/Aldehyde Ester Fluoro Chloro Bromo Iodo Ether Ester Isocyanate Amino Nitro Sulfide Sulfoxide Sulfone Sulfonate R2= none Alkyl Alkene Phenyl Ketone/Aldehyde Ester Fluoro Chloro Bromo Iodo Ether Ester Isocyanate Amino Nitro Sulfide Sulfoxide Sulfone Sulfonate R3= none Alkyl Alkene Phenyl Ketone/Aldehyde Ester Fluoro Chloro Bromo Iodo Ether Ester Isocyanate Amino Nitro Sulfide Sulfoxide Sulfone Sulfonate R4= none Alkyl Alkene Phenyl Ketone/Aldehyde Ester Fluoro Chloro Bromo Iodo Ether Ester Isocyanate Amino Nitro Sulfide Sulfoxide Sulfone Sulfonate