Raise the Hammer

A Smith: "if LRT is proven to increase city wide investment, not just localized investment around the line, please explain why it didn't work in Boston"

The simple answer to your question is, first, that Elevated trains are NOT light rail. Elevated lines do not bring the same influx of investment as street level LRT. In fact, boston started removing EL lines and replacing them with LRT or Subways:

"The removal of elevated lines continued and the closure of the Washington Street Elevated brought the end of rapid transit service to the Roxbury neighborhood. Between 1971 and 1985, the Red Line was extended both north and south

"With the 2004 replacement of the Causeway Street Elevated with a subway connection, the only remaining elevated railways are a short portion of the Red Line at Charles/MGH, the stretch of Red Line between Andrew Station [...] and proceeding southbound to either Ashmont Station on the Ashmont line or Braintree Station on the Braintree line, and a short portion of the Green Line" (http://en.wikipedia.org/wiki/Massachusetts_Bay_Transportation_Authority)

Second, Boston DID implement TRUE light rail through the very time period where you see the population growth, so by your logic, the conversion of elevated systems to true LRT is what caused the growth!

Furthermore, from your own source, "In December 1980, following a one-day shutdown due to a lack of funds, the Legislature approved plans to change the governing structure of the MBTA." (http://www.mbta.com/about_the_mbta/history/?id=970). This means, again using your logic, that it was most likely the change in governing structure of the MBTA that caused the population growth!

Setting aside for a moment your absolute inability to differentiate between correlation and causation, I encourage you to study a few more LRT cases and see what yo come up with. It should be pretty easy, most of the hard work has already been done for you here:

http://hamiltonlightrail.com/case_studie...

You might also want to bring your terminology knowledge up to speed, starting with an understanding of what exactly LRT is (hint: not elevated railways, not monorails, not subways, not streetcars, and definitely not BRT).