We undertake 3 experiments to answer the research questions of interest.
Experiment 1 evaluates the impact of the computer-based intervention, adapted to the Brazilian context, to test hypothesis 1. In September, 400,000 students will receive a text message with a link to access the online content typically used in the computer-based intervention, made available through an online platform (Qualtrics). Upon accessing the link, students will be randomized on the spot to one out of 2 different groups, with equal probability:
1- A placebo group, which will receive an online intervention about the brain; or
2- A treatment group, which will receive an online growth mindset intervention.
The placebo intervention will instruct students in this group about the brain’s features and functionalities but will not provide any information about mindset. The treatment intervention will instruct students in the treatment group about growth mindset and how to develop it. Both treatments are based on text, illustrated with a few images (keeping fidelity to prior studies, but adapting to local context). Audio recording of the texts are also made available for students who prefer that option (in case they have enough airtime credit and bandwidth to access it).
Experiment 2 aims at testing hypotheses 2, 3 and 4. Also in September, 400,000 students (with no overlap with Experiment 1) will receive 1 SMS, assigned to 1 out of 6 different groups. There is also a control group, of identical size as each of the other cells, assigned to receive no SMS, as follows:
1- Typical growth mindset intervention group ("your brain is like a muscle, ...");
2- Salience group ("we want you to stay in school");
3- High returns to effort group ("if you put more effort in, you can always improve relative to yourself");
4- Low costs of effort group ("studying is actually more fun than you might think");
5- Risk-taking group ("trying is always worth it, failure does not mean anything about your potential");
6- Future-orientation group ("when thinking about your studies, it is important to think about your future!"); or
7- A pure control group, which does not receive any text message.
Experiment 3 aims at testing hypotheses 5 and 6. From October through December, the plan is to stick to the assignment for a sub-sample of students, potentially with more messages per student per month. We plan on updating the pre-analysis plan before the end of September to specify the final sample and number of messages. That decision depends on other tests being undertaken by SEDUC together with Movva to determine the optimal trade-off between number of students impacts by the nudges and number of nudges per student per month.
If SEDUC decides to stick to 1 message per month, the plan is to repeat the messages with slight variations in framing but keeping both the assignment and the core concept within each group. Alternatively, if SEDUC decides to go with more than 1 message per month (with a smaller sample size), we will randomly draw users within each treatment arm to receive additional messages. That experiment would allow us to estimate persistence and fade-out of treatment effects, as well as saturation effects (contrasting those assigned to receive additional messages to the ones who received messages only in September, and those to the pure control group).
Additionally, we intend to embed a 4th experiment into experiment 3 to evaluate hypothesis 8, or how the computer-based intervention format interacts with the text message format. To do so, we will select a random subsample of subjects in Experiment 3, to be determined and updated here after September, to receive a text message containing the link to the computer-based treatment.