Does Extended Time Improve Students’ Performance?

Editor’s note: This post is part of a series showcasing Barcelona GSE master projects by students in the Class of 2014. The project is a required component of every master program.

Does Extended Time Improve Students’ Performance? Evidence from Catalonia


Ana María Costa Ramón, Laia Navarro-Sola, Patricia de Cea Sarabia

Master Program:


Project Summary:

Education is one of the main priorities of developed societies, and countries are investing huge amounts of resources in this area. However, little is known about the effectiveness of the inputs used in the education production function, leaving the final decision of investment to ideological or political reasons. In this context, there is an increasing support of extending class time among politicians and policy-makers as a way of improving education. Our paper is an investigation of the effect of an increase in the number of hours per day of class on the performance of the students.

As identification strategy, we exploit the exogenous variation generated by a policy change in Catalonia (a region of Spain), known as the “sixth hour policy”. This reform introduced one extra hour per day, representing an increase of 20% of the total number of hours per year. It involved an important investment for Catalonia and thus, knowing the effects of the policy is needed in order to assess whether it was effective or if there exists other alternatives. The specific characteristics of the policy implementation provide three different sources of variation: variation between cohorts, generated by the sudden implementation, variation between types of schools, since the policy was only addressed to public schools (leaving private schools timetable unchanged) and in last term, variation across regions, as the reform only affected public schools in Catalonia. These features allow us to take the policy implementation as a natural experiment and thus, to investigate more deeply the effects of extending school time.

Using the PISA database and the econometric specification of differences-in-differences, we find that there is no conclusive evidence of the causal relationship between extending school time and performance improvement. This difficulty comes from the implementation of the policy itself which was done simultaneously with other major educational changes, and thus it is hard to identify the channel through which this effect could be operating.

However, we face this lack of evidence on this causality introducing an innovative methodology in the study of extending time at school. To solve specific concerns about the suitability of the control group we construct a “synthetic control” group (an artificial control group), which is a weighted combination of other Spanish regions chosen to resemble education characteristics of Catalonia before the introduction of the “sixth hour policy” as much as possible. However, the particularities of the region of the study make it very hard to predict its behavior.

All in all, we believe that the use of the synthetic control approach can help to shed light on these issues in different case studies or with more detailed data. The analysis of time as an input in the education production function still requires a lot of research but as we have seen with our case study, natural experiments by themselves could be an imperfect tool. Maybe it is time to use more innovative approaches to this old topic.

Read the full paper or view slides below: