Questions and Answers
Who developed the method of classifying prints that allowed all sets of ten prints to be divided into 1024 groups?
What are fingerprints divided into?
more complex classifications
What does computer matching do in the context of fingerprint analysis?
makes the first list
The first step in fingerprint analysis is to identify ______.
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How are whorl patterns assigned a number?
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What is done to avoid zeros in the whorl pattern fractions?
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25% of people have loops and arches with no whorls.
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What type of fingerprint pattern is more common among individuals of African background?
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What fingerprint patterns are often found among people of European background?
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Which background shows a higher frequency of whorls?
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Which fingers are noted to have the most radial loops?
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What should be used when judging the probative value of evidence?
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What does the rule of large numbers state?
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What is the probability someone would have 2 arches if each finger has a probability of 1/20?
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In a group of 1000 people, how many arches would you find?
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Study Notes
Henry Classification System
- Edward Henry developed a method to classify fingerprints, dividing ten prints into 1024 groups; the FBI modified this system.
- Fingerprints are categorized into more complex classifications for detailed analysis.
Analysis Process
- Millions of prints can be narrowed down to a few dozen for manual comparison.
- Initial matches are generated through computer matching, but final comparisons require manual verification.
Classification Steps
- The first step in analysis is identifying whorl patterns among fingerprints.
- Whorl patterns are assigned numbers based on which finger displays the whorl, formatted as a fraction.
Adjustment Technique
- To prevent zero values, one is added to both numerator and denominator in the fraction representing finger patterns.
Population Insights
- Approximately 25% of the population exhibits loops and arches with no whorls, represented as 1/1 in the classification.
- Variations in fingerprint patterns are observed across different ethnic backgrounds:
- Individuals of African descent tend to have more arches.
- Individuals of European descent often display a higher frequency of loops.
- Individuals of Asian descent show a greater prevalence of whorls.
Finger Patterns
- The forefingers or index fingers are most likely to exhibit radial loops, which are important for classification.
Statistical Methods
- Probability is used to assess the evidential value of fingerprints in investigations.
- The rule of large numbers indicates that a larger population increases the likelihood that actual figures will resemble computed probabilities.
Probability Calculations
- The probability of an individual possessing two arches is calculated as follows: each finger having 1/20 probability results in an overall probability of 1/400, or 40 to 1 against this outcome.
- In a group of 1000 individuals, one would not necessarily find 500 people with arches, but 500 arches may exist within the sample.
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Description
Explore the Henry Classification System for fingerprints developed by Edward Henry. Learn how fingerprints are grouped, the steps in analysis, and adjustments made for accurate classification. Understand the complexities behind matching millions of prints efficiently.
