Alan-Ertac Grit and Growth Mindset Intervention Study 2 (replication)

Last registered on October 23, 2018


Trial Information

General Information

Alan-Ertac Grit and Growth Mindset Intervention Study 2 (replication)
Initial registration date
October 23, 2018

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
October 23, 2018, 9:32 PM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.



Primary Investigator

European University Institute

Other Primary Investigator(s)

Additional Trial Information

Start date
End date
Secondary IDs
The purpose of this trial is to replicate the findings of Alan-Ertac Grit and Growth Mindset Intervention Study 1 (AEA registry number: AEARCTR-0003317)

We evaluate the same program described in Trial AEARCTR-0003317 with respect to the same outcomes. The program involves an intensive teacher training program, supported by a specially designed curriculum. The curriculum consists of animated videos, mini case studies and classroom activities that highlight i) the plasticity of the human brain against the notion of innately fixed ability, ii) the role of effort in enhancing skills and achieving goals, iii) the importance of a constructive interpretation of failures and therefore perseverance, and iv) the importance of goal setting.

In this replication, we randomly assign the same grit intervention as in Trial AEARCTR-0003317 across a new set of schools in Istanbul. This sample consists of 16 schools. While the intervention follows the same procedures (same curricular materials and teacher training approach), there are a couple of important differences in the way the study was conducted. These changes were made to alleviate potential issues with the design of the first study. First, in the replication study, the treatment schools were not subject to any other treatment than grit. This allows us isolate the effect of the grit
intervention. Second, we administer our own math and verbal tests both at baseline and at

In addition to the experimental outcomes measuring grit and test scores, we evaluate this replication with respect to social preferences. In particular, we implement an altruism experiment, where we manipulate the donation context. Using a variant of the dictator game, we ask children whether they would like to donate a fraction of their experimental earnings (gifts) to anonymous children. A random half of both treated and control children are given the information that the recipient has no gifts because he/she failed at the real-effort task, while the other half are given the information that the recipient has no gifts because his/her school was not visited.

By implementing one context where the recipient’s poorness is certainly due to bad luck (not having been visited) and one where it may be due to a lack of effort, we compare the responsiveness of giving on the part of treated and untreated children to the potential reasons for the recipient’s poorness.
With respect to the effect of the program on experimental measures of grit as well as real outcomes, we replicate all our results documented in Study 1.

With respect to social preferences, we find that treated children, holding significantly more optimistic beliefs about the role of effort in success, are significantly less likely to donate their earnings to those who failed at a real effort task. These results highlight possible unintended social effects of growth mindset interventions.
External Link(s)

Registration Citation

Alan, Sule. 2018. "Alan-Ertac Grit and Growth Mindset Intervention Study 2 (replication)." AEA RCT Registry. October 23.
Former Citation
Alan, Sule. 2018. "Alan-Ertac Grit and Growth Mindset Intervention Study 2 (replication)." AEA RCT Registry. October 23.
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Experimental Details


Teachers in the treatment group received full-day training on the delivery of the curriculum. This is the same Grit curriculum described in Study 1 (AEARCTR-0003317).
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
We have two sets of outcomes:
1) Experimental outcomes
2) Achievement outcomes
Primary Outcomes (explanation)
Experimental Outcomes:
1) A novel behavioral task to elicit several facets of gritty behaviour:
a. Challenge seeking
b. Perseverance
c. Plan for higher achievement
2) Competitiveness.
3) Altruism, measured through a version of dictator game.

Achievement Outcomes:
i) Actual success in the behavioral grit task
ii) Objective test scores in math and Turkish (in two follow-ups)
iii) Teacher-given grades in math and Turkish

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We sampled 16 schools and collected baseline information. We randomly allocated 8 schools to treatment, 8 to control. Teachers in the treatment group received training on our grit curriculum and nothing else. After the intervention ended, there were two follow-up data collection phases. In the first follow-up, experimental measures on grit, competition, and altruism were collected, along with objective test scores. In the second follow-up, longer-term effects on objective test scores were measured.
Experimental Design Details
Randomization Method
Teachers in designated schools were called in a random manner. A willing teacher was assigned 50% probability to be in treatment group. Using Stata’s uniform random number generator, we performed the assignment.
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
16 schools.
Sample size: planned number of observations
Official student number is 1499
Sample size (or number of clusters) by treatment arms
Official student number for Treatment= 8 schools (683 students), Control= 8 schools (816 students), Total = 16 schools (1499 students).

Official sample size corresponds to all registered students in participating schools.
Sample size for experimental outcomes is lower because these outcomes were collected from students who were present at the time of the classroom visits.

Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
We calculate the smallest real effect sizes that we can detect at a 5% significance level with 80% power. We perform the calculation based on 8 treatment and 8 control clusters with approximately 94 students per cluster. Below we display the mean, standard deviation, intracluster correlation coefficient (ICC) and minimum detectable effect (MDE) sizes for our main outcome variables: (i) math and verbal grades given by teachers, (ii) math and verbal test scores as measured using standardized achievement tests, and (iii) experimental choices and outcomes, which comprise students’ choice of the difficult task in round 1, students’ choice of difficult tasks in all five rounds of the first visit, students’ choice of the difficult task for the following week, and students’ total payoff from the experiment. Grades and achievement test scores are standardized to have a mean of zero and a standard deviation of one. When calculating the ICC and MDE for grades and test scores, we take into account that we have baseline information on students’ gender, baseline beliefs and test scores, student ability as measured by the Raven test and class size by first regressing the outcome variable on the baseline characteristics and performing the ICC and MDE calculations using the residuals from that regression. Variable Mean SD ICC MDE In SD/% Math grade 0.00 1.00 0.094* 0.30* 0.30 SD Verbal grade 0.00 1.00 0.139* 0.37* 0.37 SD Math score 0.00 1.00 0.002* 0.13* 0.13 SD Verbal score 0.00 1.00 0.008* 0.15* 0.15 SD Choose Difficult (Round 1) 0.77 0.42 0.026 0.11 15% Choose Difficult (All Rounds 1-5) 0.22 0.41 0.008 0.08 36% Choose Difficult (Second Visit) 0.50 0.50 0.041 0.16 32% Total Payoff 2.86 2.35 0.017 0.54 19% (*) ICC and MDE for grades and test scores calculated using baseline information.

Institutional Review Boards (IRBs)

IRB Name
Koc University IRB
IRB Approval Date
IRB Approval Number


Post Trial Information

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials