No, Peopleware's research was on the productivity of individuals at different organizations. To be precise what they did is arranged a series of "coding wars" where multiple organizations would each select 2 individuals and all would code up solutions to the same problem in the language of their choice. People were asked to keep a log of what they did, and describe various things about their environment.

They found an order of 10 productivity difference that showed up under any of a number of possible measures. The also found that the best predictor of a given person's productivity was the productivity of the other person from the same organization. They also identified a number of workplace environment issues that were strongly correlated with productivity.

This overall picture comes with many caveats. Individual productivity differences were still quite significant. They didn't have any way to tell correlation versus causation. (To what extent does a better environment make programmers better, versus correlate with being able to hire and retain them?) The coding assignments were fairly small. So don't read too much into the result.

But given the size of the difference, and that it is one of the few attempts to quantify these issues, it isn't a result to take lightly either.