4. Imagine you are testing a crime scene DNA sample. While it is standard
for forensic scientists to examine at least 20 STR locations to create a DNA
profile, this has not always been the case.
a. Multiply the genotype frequencies in Table 2 to calculate the
random match probability for this STR profile using the product rule.
Show your work.
Type your answer here.
b. Scientific notation is often used with very small numbers. Compare
the random match probability that you just calculated with the
scientific notation to the right. What order of magnitude is the
random match probability?
Table 3
Scientific
notation
In fraction form In words
1E-6 1/1,000,000 one in a million
1E-9 1/1,000,000,000 one in a billion
1E-12 1/1,000,000,000,000 one in a trillion
i. On the order of one in a million
ii. On the order of one in a billion
iii. On the order of one in a trillion
c. How confident would you be in using this DNA sample to convict
someone of a crime?
Type your answer here.
Electrophoresis Forensics Lab: Wrongfully Convicted? Student E-worksheet™.
Release: September 2023. © 2023 by miniPCR bio
TM
