st: Nested design problem

[Steven Raemaekers <s.raemaekers@sig.eu>]

Hello,

I do not know where else to post this problem so I hope somebody can help me here. I have a statistical design issue which is as follows.
As an example, let's say I have a table with information on people in the following format:

Id			IQ		Introvertness		…
person1		120		80				…
person2		110		70				…
person3		130		40				…

This table contains a number of properties of certain persons, each person is a unique entry in this table. I also have a table which contains relationships between those persons: 

Id1		Id2		Closeness	
person1	person2	80
person1	person3	70

"Closeness" is a property of the relationship between person1 and person2. The numbers do not make sense but are just for illustration.

Now I want to test whether people that are in relationships "closer" to each other are more intelligent. I also possibly want to take into account other properties of people. 
In regression terms: I want to regress the dependent variable IQ on the independent variable closeness and introvertness. How can I do this? 

The problem is, persons can appear multiple time in the list so applying normal linear regression or correlation on this table produces incorrect results. 
Additionally, there are two sides to the relationship, so there is a connection between the IQ of person1, the closeness of their relationship and the IQ of person2.
I believe the thing I need is called a nested hierarchical model/mixed model, but I have no idea how to design this. 

My questions are therefore the following: 
1) What statistical test do I need to test my hypothesis on this data? 
2) What assumptions does this test make and how can I check these assumptions?
3) How should I format my data? 
4) What are the commands in Stata to execute this test? 

Thanks very much! 

Regards,

Steven Raemaekers
PhD student
Software Improvement Group/TU Delft

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