But it could also be that not all the living tree samples were available before; the timeline for taking of the samples is not clear. (deepclimate.org)
When this record was combined with the other tree samples, we went back about 1,100 years in all — that was really astounding. (discovermagazine.com)
The other flaw was a failure to account for differences in the number of trees sampled at each corner. (sciencedaily.com)