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DNA - A Prosecutor’s Practice Notebook Inventory

Single Source Sample v. Mixed Sample

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The product rule should be used when the evidence is from a single source or if there is a predominate DNA profile in a mixture. Mixtures can complicate a statistical calculation. 

A typical statistic might state that the evidence DNA profile may occur 1 in every 1,000,000 people in the general population. This would also mean that 999,999 of every 1,000,000 people would NOT be expected, or are excluded as persons who would be expected, to have this profile.

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