The real story behind the Unix 'survey'
By surenssamant on Jan 05, 2006
Last month, there was a 'survey' on Unix server users' vendor preferences by a group named GCG. The result of the 'study' seemingly showed Sun slipping behind IBM and HP, and was widely picked up by media without going into facts per se. Later, Paul Murphy came out with the real facts the study obviously (or deliberately) ignored.
In short, the study used something called VPI to calculate a vendor's score. Out of 197 respondents selected for the survey, let's say Sun is primary vendor for 140 of them(as the largest Unix vendor). Most of the customers have more than one vendor. For any metric, if 120 out of total 197 vote for Sun as preferred vendor, it should be 120/197 = 61% ?
OTOH, if HP has 40 customers and for the same metric as above, if 44 vote for HP it should be 44/197 = 22%.
Now here is the interesting part. According to that 'survey' HP beats Sun in this metric. Why? They calculate something called Vendor Preference Index (VPI) which is even more interesting. They calculated it by dividing the number of votes a vendor gets by number who use the vendor's Unix.
Going by this, HP gets 44/40 = 1.1 VPI and Sun gets 120/140 = lowly 0.85!
So even though Sun has 61% of respondents giving it thumbs up as compared to HP's 22%, HP actually beats Sun if you go by VPI and the 'survey'!
The calculation goes on for many metrics and, as expected, results are heavily skewed against Sun.