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MozTrust and PageRank and two very different metrics. MozRank is calculated in a similar way to PageRank while MozTrust, as James explained, is used to determine if you are a trusted source by measuring your distance to other trusted sources. Here is an interesting article that explains how MozRank is calculated and how closely it related to Google's PageRank. http://www.seomoz.org/blog/mozrank-and-pagerank-for-metrics-driven-seo