So, how can you verify that only embedded developers / engineers are answering the survey?
I can`t do that in the middle of the research. But I can do that through analysis later, while looking for answers that were just for the sake of answering or for "lurkers". But I doubt a lot of non embedded developers and engineers are going to take the survey, since it is not easy to find actual developers/engineers to take the survey. And even if a few of them slips through it is not a problem for analysis.