I use the g, h-index
(http://en.wikipedia.org/wiki/H-index) and related numbers to show wy some thinkers, like Althusser, who are in all bibliographies in educational sciences have a less impact than others comparing different sources of information (Google Scholar, general purpose search engines and others) and learning university bibliography uploaded into teachers pages - via a statical querying.
Also, for those teachers that includes Althusser in their bibliographies, I was envoy an questionnaire to eval if it's true that they show him in class.
So, I extended the analysis for other areas that the original purpose of the index. I think that the same thing can be done between the 4M; in this case probably restricted in first instance to those two that have not common meaning.
But without analyse too much, with simple searching in Google:
matlab:.........5,790,000
mathcad:..........777,000
Correlates very well with the relationship between
Chomsky:........1,450,000
Althusser:........182,000
A plausible declination because originally publish in French can be estimated regarding some index from others non english authors:
"Paulo Freire":...670,000
(Here excluding Freire's that aren't Paulo)
Thesis to prove is: even academic bibliography index are good, a temporal declination in general searching engines ensure less influence. Learned as: a modest marketplace, if the subject it's a software.
Regards. Alvaro.