Register to reply

Geneaolgy Research - Probabilty of Someone having the same name

by berksted
Tags: geneaolgy, probabilty, research
Share this thread:
Jun1-10, 10:30 PM
P: 6
I never posted in this forum, so if this questions is not relevant, please let me know. I have a family member trying to trace the biological father of my adopted grandfather. From his adoption records she has been able to find a person who matches his name - first, middle and last as well as the same birthday. The last name is Smith so it's common but this was also Minnesota in 1907 (population not too large). I think we have found the right person, but what are the odds of someone having the same name and birth date in a given year.

Since some names are more common that others, I realize this is difficult problem to actually compute, but how does one think about this type of probability?
Phys.Org News Partner Science news on
Physical constant is constant even in strong gravitational fields
Montreal VR headset team turns to crowdfunding for Totem
Researchers study vital 'on/off switches' that control when bacteria turn deadly
Jun2-10, 12:24 AM
Sci Advisor
HW Helper
P: 3,682
It's a hard problem because names aren't independent. A "Smith" is more likely to be a "Lawrence" than a "Maurice" (though they're of similar popularity in the overall population).

Toward a first approximation, since Smith is a popular name, I would check records (whatever you can find... SS death records if nothing else, though use a later date in that case) to see what percentage of Smiths in Minnesota have a matching first name and what percentage have a missing last name. Multiply those probabilities together then by the number of people in your database (hopefully not the same one you used to get the percentages) to get a rough first guess of how many matches you'd expect through chance alone. If it's small, there's a good chance that's the one.
Jun2-10, 10:32 AM
P: 103
Randomly pick 6 people from the street. The probability for at least 3 of them have same name or at least 3 of them have different name equals to 1.

Jun2-10, 11:23 AM
P: 1
Geneaolgy Research - Probabilty of Someone having the same name

This is common problem, I read some other threads & this is so interesting, if anyone who is know more about it so please reply, and I found such useful lab notebook software for researchers & developers.

Register to reply

Related Discussions
Help with conditional probabilty Set Theory, Logic, Probability, Statistics 8
Probabilty distribution? Precalculus Mathematics Homework 2
Probabilty of AnB Set Theory, Logic, Probability, Statistics 2
Probabilty Problem Set Theory, Logic, Probability, Statistics 3
What is a probabilty wave? Quantum Physics 2