[igraph] interpretation of hub/auth scores

[Matthew Galati]

I am considering this small directed graph. 

The results score node 1 as the dominate hub and the rest of the nodes with value 0 (i.e., no' hubness'). This seems odd to me. For example, node 2, has outlinks to 3 different nodes (1,4, and 7). So, I would expect it to have some relative level of hubness.

> g <- graph.empty()

> g <- g+vertices(1,2,3,4,5,6,7)

> g <- g+edge("1","2")

> g <- g+edge("1","3")

> g <- g+edge("1","5")

> g <- g+edge("1","6")

> g <- g+edge("2","1")

> g <- g+edge("2","4")

> g <- g+edge("3","1")

> g <- g+edge("5","1")

> g <- g+edge("2","7")

> E(g)

Edge sequence:

         

[1] 1 -> 2

[2] 1 -> 3

[3] 1 -> 5

[4] 1 -> 6

[5] 2 -> 1

[6] 2 -> 4

[7] 3 -> 1

[8] 5 -> 1

[9] 2 -> 7

 

> hub.score(g,scale=FALSE)$vector

        1         2         3         4         5         6         7 

0.5733822 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000