Stat 407 Quiz 2 Fall 2001
Name
1. (2pts) Which of the following linkage methods for hierarchical clustering is the most likely to give the
following grouping of cases into cluster 1 and cluster 2? Explain.
(a) Single , (b) Complete,
(c) Wards
(d) Average.
2. (2pts) On the above plot draw your guess at the solution that would be provided by k-means clustering,
with k = 2. Explain.
3. (1pt) Fuzzy c-means is a variant of the k-means clustering algorithm. (T or F)
1
4. (2pts) From this formula for a bivariate normal density tell me what the mean is and the variance-covariance
of the distribution is.
f (x1 , x2 ) =
1
4 2
2π 2 5
1/2
1
× exp{− (x1 + 5 x2 − 2)
2
"
5/16 −1/8
−1/8 1/4
#
x1 + 5
x2 − 2
!
}
5. (2pts) Which of the following is most likely not a sample from a normal distribution? Explain.
6. (1pt) Mahalanobis (or statistical) distance derives from the exponent of the multivariate normal density
function. (T or F)
2