Kaya Henderson testified at the City Council hearing yesterday that the new teachers who have been hired over the past four years (i.e., under the watch of Rhee and Henderson) are better than those whom they replaced (like me).
Does she have any evidence to back this up?
I doubt it.
My own research shows that there is essentially NO correlation between the median hire date of the staff at a school and the percentage of students at that school who were deemed “proficient” or “advanced” in math on the last DC-CAS of April 2011.
Look for yourself.
If having a brand-new staff was strongly correlated to higher scores, and having a veteran staff were likewise correlated with lower scores, then the graph would look something like this:
And if having veteran teachers guaranteed higher test scores, then the graph would look something like this:
That is, in the first hypothetical case, the overall slope of the data points would go up and to the right (and down to the left). In the second hypothetical case, the slope of the data points would be the opposite, i.e. from upper left to lower right.
Neither case holds water (all I did is delete some of the points).
Evidently, this much-vaunted churning of staff at most DC public schools has produced essentially NO good results. Just like everything else that the Chancellors have done.