Miscellaneous Ridge Formation Types

In the event a quantitative weight is needed for a ridge event that has not been previously established, then a frequency of occurrence study for that particular ridge event should be performed.  For example, if the quantitative weight for a “wart” mark is needed, then a sample of flat fingerprints selected at random from ten-print files may be used for a frequency of occurrence study.  The number of times a wart unit appears is used to define its frequency of occurrence. 

The formula used to establish the probability (P) for an unlisted ridge formation (X), where X equals the number of times the unlisted ridge formation occurs in 23,136 .45mm x .45mm cells within a sample of 39 flat fingerprints is as follows:

Note:  The National Research Committee (NRC) on DNA guidelines recommends a value of 5/N for any allele that is not found in a the sample population [101]. In accordance with NRC guidelines, a similar frequency of 5/23,136, equivalent to a probability of 1/4,627.2  may be desired for purposes of added conservativeness. 

However pending continued validation studies, at this time the quantitative weight of 23,136, and probability of 1/23,136, is applied as the default value for ridge formations not found in a given fingerprint sample.

 

Example

What is the quantitative weight for a wart formation?

Based on a frequency study, no wart formations were found.  As a result the value for a wart formation is defined as 23,136.  As a result it's probability is defined as 1/23,136.

Based on the theory that the product of the parts equals the whole, if only parts of a miscellaneous ridge formation match, then the value for each part multiplied against itself should equal the whole. 

 
Example

A wart formation in an impression, for example, matches parts of a wart  formation in another impression, then the number of parts should be defined in order to determine the value for each part.  If the number of parts equals N, and the value for each part equals P, then based on the theory that the product of the parts equal the whole, the following formulae is applied to define the value for P:

N^P=23,136 

Let the number of total wart parts equal 10 and the number of matching wart arts equal 5.

If P = 10, then N = 2.7316 

As a result, the aggregate weight or the 5 matching wart parts may be defined as follows:

4.3642 ^ 5 =  152.10

The subsequent match probability is defined as 1/152.10.