Calculation of Mixture Statistics Using Popstats - Promega

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HOW TO EXPRESS THE NUMBERS FROM LIKELIHOOD RATIO COMPUTATIONS When making statements on the statistical inferences remember that you are expressing only the genetic data You are not dealing with issues of “chance” To do so would involve Bayesian inferences which include Prior Probabilities…for which genetic data offers little assistance.
So, with regard to Defense Hypothesis 1 we could say: The observed mixture profile is 9- times more likely to occur under the scenario that it is a mixture of DNA from the victim and suspect, as opposed to the scenario that it originated from a mixture of DNA of the victim and an unrelated unknown person.
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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
Page 13 and 14: Exclusion Probability This is a mea
Page 15 and 16: For example: Exclusion Probability
Page 17 and 18: Exclusion Probability The probabili
Page 19 and 20: Exclusion Probability In presence o
Page 21 and 22: Exclusion Probability What does thi
Page 23 and 24: We have the following data: Mixture
Page 25 and 26: Given that both victim and suspect
Page 27 and 28: What if we couldn’t assume H-W? P
Page 29 and 30: How does PopStats handle this calcu
Page 31 and 32: Here is the input data But what is
Page 33 and 34: It is the compliment of Inclusion P
Page 35 and 36: PE = 1 - 8.033 X 10 -7 = 0.99999919
Page 37: What if we have to consider some al
Page 40 and 41: Mixtures and Likelihood Ratios Like
Page 42 and 43: Let’s use the same example used i
Page 44 and 45: Three Alleles Victim is heterozygot
Page 46 and 47: The prosecution may postulate that
Page 48 and 49: The defense might argue that the fo
Page 52 and 53: Since the victim has the profile (8
Page 54 and 55: Now here is where the “RATIO” i
Page 56 and 57: Defense hypothesis 2 is a little mo
Page 58 and 59: How do we get these probabilities?
Page 60 and 61: Of course…we could incorporate θ
Page 62 and 63: What next… The total probability
Page 66 and 67: Conservative Basic True!
Page 68 and 69: Or The probability (chance) that th
Page 70 and 71: Assumptions In Likelihood Computati
Page 72 and 73: Assumptions In Likelihood Computati
Page 74 and 75: So, lets go back to our previous da
Page 76 and 77: And our "K1" and "K2" genotypes:
Page 78 and 79: Our entry data from before:
Page 80 and 81: This side will autofill when changi
Page 82 and 83: C2 reflects the H a H a = The resul
Page 84 and 85: Notes: • The layout screen is pos
Page 86 and 87: Ok… so what do we get when we pus
Page 88 and 89: 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 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
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Under the Prosecution’s hypothesi
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Unk 1 Unk 2 A1A2 A1A2 A1A2 A1A3 A1A
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The Likelihood Ratio becomes: p 3 2
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p 1 = 0.1, p 2 = 0.2, and p 3 = 0.3
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So, with regard to the Defense Hypo
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Of course we can do this in PopStat
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Of course we can do this in PopStat
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Now…Let's have some real fun! Sce
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Our Knowns: Let's see how this scen
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H a1 = The results are explained by
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Our Results:
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The "profile" in C1 represents all
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Our Results:
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Considerations Unlike interpretatio
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Considerations Most critical step o
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Calculation of Mixture Statistics Using Popstats - Promega

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