In this case it's not grammatically incorrect, but poor style. "Therefore" binds cause and effect. "As such" binds subjects.
This would be correct:
Tim had an accident, totalled the car and broke his leg. As such, he's not in condition to go to work.
It is clear the other clause is speaking about Tim.
Tim had an accident, totalled the car and broke his leg. As such, I can't lend it to you because it's totally junk now.
This is poor style, it's not clear you're talking about car. "As such" would normally apply first to Tim, then "As such, I" would seem that you are not in condition to lend the car, and in the end only the it clarifies it's the car that is "such as in the first sentence"
Tim had an accident, totalled the car and broke his leg, so I can't lend it to you because it's totally junk now.
Tim had an accident, totalled the car and broke his leg. Therefore, I can't lend it to you because it's totally junk now.
makes the sentence okay. "Therefore" (or plain, much less fancy ", so") connects the cause - the accident, with the effect - your inability to lend the car.
In your specific case, the first sentence has several subjects: calculations, teachers, effects, college going, wages (both real and predicted), and test scores. Then comes "as such, the teachers" - and you need to backtrace: "What was the teachers' situation from the first sentence? I thought it was about the calculations, or the effects. So, teachers again?"
This might be remedied by either using "therefore", "as result", "so", or rephrasing to make the teachers a clear, primary subject:
Teachers, as additional calculations suggest, have effects on college going and wages, that may be as much as three times larger than predicted based on test scores alone. As such, more than half of the teachers...
In this case you know what is the focus subject, and don't need to hunt for it when using "as such".