I tend to comment on newly-released teacher surveys, primarily because I think the surveys are important and interesting, but also because teachers' opinions are sometimes misrepresented in our debate about education reform. So, last year, I wrote about a report by the advocacy organization Teach Plus, in which they presented results from a survey focused on identifying differences in attitudes by teacher experience (an important topic). One of my major comments was that the survey was "non-scientific" – it was voluntary, and distributed via social media, e-mail, etc. This means that the results cannot be used to draw strong conclusions about the population of teachers as a whole, since those who responded might be different from those that did not.
I also noted that, even if the sample was not representative, this did not preclude finding useful information in the results. That is, my primary criticism was that the authors did not even mention the issue, or make an effort to compare the characteristics of their survey respondents with those of teachers in general (which can give a sense of the differences between the sample and the population).
Well, they have just issued a new report, which also presents the results of a teacher survey, this time focused on teachers’ attitudes toward the evaluation system used in Memphis, Tennessee (called the “Teacher Effectiveness Measure," or TEM). In this case, not only do they raise the issue of representativeness, but they also present a little bit of data comparing their respondents to the population (i.e., all Memphis teachers who were evaluated under TEM).