Compute SPEI using HAPPI data

[ploan]

I just wonder whether we can compute SPEI based on HAPPI data which has a temporal coverage of 10-year ? As McKee et al., 1993 suggest that the analysis and calculation of drought characteristics need data from a long-term period of typically > 20 consecutive years.

If I use 10-year dataset, the result will be accurate and realizable?

[sbegueria]

You could use 10 years, but I'd say that's too short.