Calculation of Mixture Statistics Using Popstats - Promega

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Considerations Unlike interpretation of single donor profiles, the relevant questions for mixture interpretation can be varied, and a wider set of scenarios with respect to the origin of the mixture may be postulated…each hypothesis is mutually exclusive and applies a different treatment of the data
Considerations Subtraction of alleles found in the known samples from the mixture should be avoided in deriving statistics for mixture interpretation. This adds to conservatism, even with the use of the simplest assumption in calculations.
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Popstats Unplugged 14 th Internatio
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What Constitutes a DNA Mixture? Pr
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What Constitutes a DNA Mixture? Ci
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Common Mixture Interpretations Alle
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But, before we begin… Calculation
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Two common questions are generally
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Exclusion Probability This is a mea
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For example: Exclusion Probability
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Exclusion Probability The probabili
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Exclusion Probability In presence o
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Exclusion Probability What does thi
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We have the following data: Mixture
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Given that both victim and suspect
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What if we couldn’t assume H-W? P
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How does PopStats handle this calcu
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Here is the input data But what is
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It is the compliment of Inclusion P
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PE = 1 - 8.033 X 10 -7 = 0.99999919
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What if we have to consider some al
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Mixtures and Likelihood Ratios Like
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Let’s use the same example used i
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Three Alleles Victim is heterozygot
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The prosecution may postulate that
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The defense might argue that the fo
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The defense might argue that the fo
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Since the victim has the profile (8
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Now here is where the “RATIO” i
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Defense hypothesis 2 is a little mo
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How do we get these probabilities?
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Of course…we could incorporate θ
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What next… The total probability
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HOW TO EXPRESS THE NUMBERS FROM LIK
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Conservative Basic True!
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Or The probability (chance) that th
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Assumptions In Likelihood Computati
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Assumptions In Likelihood Computati
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So, lets go back to our previous da
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And our "K1" and "K2" genotypes:
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Our entry data from before:
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This side will autofill when changi
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C2 reflects the H a H a = The resul
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Notes: • The layout screen is pos
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Ok… so what do we get when we pus
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Big Number Names: • 1,000,000 mil
Page 90 and 91: You could also look at what the all
Page 92 and 93: C2 reflects the H a H a = The resul
Page 94 and 95: You can drag and drop the entire fi
Page 96 and 97: Continue, holding the SHIFT button
Page 98 and 99: Big Number Names: • 1,000,000 mil
Page 100 and 101: Lets look at a different scenario O
Page 102 and 103: Two alleles match the suspect - A 1
Page 104 and 105: The prosecution may postulate that
Page 106 and 107: The defense might argue that the fo
Page 108 and 109: The resulting likelihood ratio is:
Page 110 and 111: So, with regard to Defense Hypothes
Page 112 and 113: Same question as before but… Thre
Page 114 and 115: Under the Prosecution’s hypothesi
Page 116 and 117: Unk 1 Unk 2 A1A2 A1A2 A1A2 A1A3 A1A
Page 118 and 119: The Likelihood Ratio becomes: p 3 2
Page 120 and 121: p 1 = 0.1, p 2 = 0.2, and p 3 = 0.3
Page 122 and 123: So, with regard to the Defense Hypo
Page 124 and 125: Of course we can do this in PopStat
Page 126 and 127: Of course we can do this in PopStat
Page 128 and 129: Now…Let's have some real fun! Sce
Page 130 and 131: Our Knowns: Let's see how this scen
Page 132 and 133: H a1 = The results are explained by
Page 134 and 135: Our Results:
Page 136 and 137: The "profile" in C1 represents all
Page 138 and 139: Our Results:
Page 142: Considerations Most critical step o
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Calculation of Mixture Statistics Using Popstats - Promega

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