6/3/13
Quiz Feedback | Social and Economic Networks: Models and Analysis
Feedback — Quiz Week 2
You submitted this quiz on Sun 2 Jun 2013 11:39 PM IST (UTC +0530). You got a
score of 16.00 out of 16.00.
Question 1
Which of the following is NOT evidence for Homophily?
Your Answer
Score
Explanation
Scholars with similar ethnic background are more likely to
coauthor;
Venture capitalists who graduated from the same universities
tend to invest together;
There are usually an equal number of boys and girls in a
preschool.
Total
✔
2.00
2.00 /
2.00
Question Explanation
Homophily refers to the fact that people are more prone to maintain relationships with people
who are similar to themselves.
Question 2
What is the (normalized) degree centrality of node 1?
https://class.coursera.org/networksonline-001/quiz/feedback?submission_id=156390
1/6
6/3/13
Quiz Feedback | Social and Economic Networks: Models and Analysis
Your Answer
Score
Explanation
2
1/3
4
1/4
Total
✔
2.00
2.00 / 2.00
Question Explanation
Degree centrality = degree / (n-1). Now degree of node 1 is 3, and n=13, so 3/(13-1) = 1/4
Question 3
What is the closeness centrality of node 1?
Your Answer
Score
https://class.coursera.org/networksonline-001/quiz/feedback?submission_id=156390
Explanation
2/6
6/3/13
Quiz Feedback | Social and Economic Networks: Models and Analysis
1
4/7
3/5
4/5
✔
Total
2.00
2.00 / 2.00
Question Explanation
Closeness centrality = (n-1) / {\sum}_j l(i,j). Now n = 5, and the denominator is 1+1+1+2 = 5, so
the answer is 4/5.
Question 4
What is the decay centrality of node 1, with \delta = 0.5 ?
Your Answer
Score
Explanation
1.25
1.75
✔
2.00
2
2.25
Total
2.00 / 2.00
https://class.coursera.org/networksonline-001/quiz/feedback?submission_id=156390
3/6
6/3/13
Quiz Feedback | Social and Economic Networks: Models and Analysis
Question Explanation
Decay centrality = {\sum}_j \delta ^ {l(i,j)}, hence 0.5+0.5+0.5+.25 = 1.75.
Question 5
Compare nodes 3 and 4: which one has a larger betweenness centrality but a lower Bonacich
centrality (b=1/3)?
Your Answer
Score
Explanation
Node 3
Node 4
Total
✔
2.00
2.00 / 2.00
Question Explanation
Node 4 is correct.
Node 3 has a betweenness centrality = 0.5, and Bonacich centrality = 13 (when b=1/3);
Node 4 has a betweenness centrality = 0.6, and Bonacich centrality = 11 (when b=1/3);
The results are provided in page 50 in the slides of Week 2.
Question 6
Consider all undirected networks with 3 nodes {1,2,3} - there are 2^3=8 networks in total. Which
of the following is the property the every node has at least one link: A(N)={g | N_i(g) is nonempty
https://class.coursera.org/networksonline-001/quiz/feedback?submission_id=156390
4/6
6/3/13
Quiz Feedback | Social and Economic Networks: Models and Analysis
for all i in N} ?
Your Answer
Score
Explanation
{1, 2, 3}
{12, 23, 13}
✔
{ {12,23},{13,23},{12,13},{12,23,13} }
2.00
{ {12},{13},{23} }
Total
2.00 / 2.00
Question Explanation
{ {12,23},{13,23},{12,13},{12,23,13} } is correct.
There are 4 networks in A(N): 3 networks {12,23},{13,23} and {12,13}, each of which has 2
links; and {12,23,13}, which has 3 links.
Question 7
Consider generating Poisson random networks on 1100 nodes where each link has a probability
p. Out of the options for p below, which is the lowest for which the networks are still likely to be
connected? So, which is the lowest number that is still larger than the threshold for connection?
[Hint: log(1100)=7 ]
Your Answer
Score
Explanation
0.1
0.001
0.01
✔
2.00
0.2
Total
2.00 / 2.00
Question Explanation
The threshold for the connectedness is t(1100)=log(1100)/1100 = 0.0064. So with p=0.01, 0.1
or 0.2, networks are all very likely to be connected. So 0.01 is the correct answer.
https://class.coursera.org/networksonline-001/quiz/feedback?submission_id=156390
5/6
6/3/13
Quiz Feedback | Social and Economic Networks: Models and Analysis
(See "A Threshold Theorem" in page 101 of the slides)
Question 8
The Small-World model in Watts and Strogatz (1999) shows that by randomly rewiring a small
but nontrivial fraction of links from a highly structured lattice:
Your Answer
Score
Explanation
Degree distributions observed in practice are matched.
It is impossible to generate both high clustering and low
diameter in one model.
Networks with high clustering and high diameter are
generated.
Networks with high clustering and low diameter are
✔
2.00
generated.
Total
2.00 /
2.00
Question Explanation
Watts and Strogatz (1999) provides a simple procedure to generate networks that have both
high clustering and low diameter, both of which occur often in observed networks. The model is
not great at generating degree distributions that match observed ones.
https://class.coursera.org/networksonline-001/quiz/feedback?submission_id=156390
6/6