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The IPDV shows similar behavior to the average RTT:
We then looked to see what portion of the larger IPDV early in the year was related to adding now monitoring and remote hosts. If we select the same host-pairs in both say Nov 2010 and April 2010 then the improvement ((ipdv(Apr)-ipdv(Nnov))/ipdv(Apr) in IPDV is about 47%. Thus things have improved with lower IPDVs for the selected host pairs.
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We also looked at the growth in the number of monitors and host pairs being monitored over 2010, see below: 
It is seen that between May and Jun the number of pairs rises significantly, prior to this there are less than 100. It is suspected taht that this is partially the cause of the more stable values of IPDV following this date.
Returning to the average RTT graph, we believe it is less confusing to mainly focus on the data from May 2010 onwards, in order to remove the effects of small statistics. In this case, the average RTTs from Jun through November 2010 have been pretty flat.
Differences in RTTs for regions
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