Remember those variables we referred to in the last video as controlled or
lurking variables.
In the example of true grit, we did take some of those into account.
So we looked at things like, teacher demographics, teacher leadership
information available at the time of hire, and what the teacher actually taught.
However, there are other variables that could explain the relationship between
grit and effectiveness that we didn't measure.
So maybe it's not grit that causes teachers to be more effective,
maybe it's something else like teacher optimism, for example.
That's related to grit but actually explains differences in effectiveness.
Whenever you're reading a study think about other explanations that
could have explained the result that the author didn't take into account.
That's internal validity.
The second type of validity to consider is external validity.
External validity captures whether the results will translate to
other populations.
So for example, we need to consider if and
how our results will translate to different settings,
different groups of people, different places, and different times.
Take the example of true grit where we studied a specific population of teachers.
They were in their first two years in teaching in urban settings.
Had relatively high SAT scores and DPA's.
And had support from a teacher training organization throughout their
first two years.
So we have to ask ourselves if these results would translate to other settings.
Would grit predict defectiveness and
retention among more experienced teachers in non urban settings.
When teachers came from less selective colleges.
Now, whenever you're reading a study, think about the extent to
which the results will generalize to other populations.