Hartley nodded. "So we keep the software, but we train Mr. Abel on it too."
Lena sighed. "That’s not simple. That’s a . Ms. Chen is a star teacher. Her kids were already scoring 15% higher before the software. If her class does better afterward, was it the software or just… Ms. Chen?" quasi-experimentation a guide to design and analysis pdf
Hartley frowned. "So I should flip a coin? Randomly assign kids to software or no software?" Hartley nodded
"Lena, look," Hartley said, tapping his desk. "I installed it in Ms. Chen’s third-grade class. She’s our best teacher. The other third-grade class, Mr. Abel’s, is using the old curriculum. After three months, I’ll compare their test scores. Simple, right?" "That’s not simple
But to be rigorous, she added a and used Huber-White robust standard errors (because monthly scores from the same class aren’t independent — a key point from quasi-experimental guides).