Question

Difference in Differences In the problems on this page, we are going to examine a hypothetical study on the effects of using interactive digital touch screens as the main instruction medium on test scores. There are two major states in a country: state A and state B. These two states were formerly one state but splits in the year 2030 forming the 2 separate states. Unsurprisingly, they are both very similar in terms of demographics, economy, climate, and other characteristics. In 2032, the state B education board mandated that every secondary school switch from chalkboards to large interactive digital touch screens (which can be written on using a digital pen) as the main instruction medium in classrooms. State A did not make such a change and remained with chalkboards. A difference-in-differences study was carried out to ascertain the effects of using the interactive touch screen on the test scores of the students on the general college entrance exam (GCEEX). The model is as follows: Y = a + BB: + P: +8B; *P;+e where • Yi denotes the average GCEEx score from schooli; • B; is the indicator which takes the value 1 if the school was from state B and Oif from state A; • Pi is the indicator (irrespective of state) which takes the value of 1 for average GCEEX scores obtained after year 2032 (when digital touch screen were introduced in state B) and 0 for before 2032. Finally, we are to assume that 40 students took the exam from each school each year, irrespective of state, so that taking the average of the school scores are the same as taking the average over all students in the state. Interpreting the model 1 point possible (graded, results hidden) Which of the following expressions gives the estimate of the mean GCEEx score for state A students after 2032, when digital touch screen were introduced in state B? Oŷ 8 O ŷt O ôtôt Oôt O Řt

Answer 1

since school was was from state A,
Bi = 0
and year is after 2032,
Pi = 1

hence

y^ =

åt

option D) is correct

although option B) is also the same