Calculation of Mixture Statistics Using Popstats - Promega

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How about an example… A mixture sample shows alleles 7, 8, and 9 at the THO1 locus. The evidence is from a semen stain found inside the pantyhose of a victim who claimed to have been raped.
We have the following data: Mixture Alleles … 7, 8, 9 Victim Alleles … 8, 9 Suspect Alleles … 7, 8 Neither the suspect nor the victim can be excluded as part contributors in the DNA of the mixture But, who else can?
Page 1 and 2: Popstats Unplugged 14 th Internatio
Page 3 and 4: What Constitutes a DNA Mixture? Pr
Page 5 and 6: What Constitutes a DNA Mixture? Ci
Page 7 and 8: Common Mixture Interpretations Alle
Page 9 and 10: But, before we begin… Calculation
Page 11 and 12: 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: Exclusion Probability What does thi
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 50 and 51: 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 64 and 65: HOW TO EXPRESS THE NUMBERS FROM LIK
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
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C2 reflects the H a H a = The resul
Page 94 and 95:
You can drag and drop the entire fi
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Continue, holding the SHIFT button
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Big Number Names: • 1,000,000 mil
Page 100 and 101:
Lets look at a different scenario O
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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
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The resulting likelihood ratio is:
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So, with regard to Defense Hypothes
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Same question as before but… Thre
Page 114 and 115:
Under the Prosecution’s hypothesi
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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
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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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