The shadow education market in Portugal: A Discrete Choice Experiment

Last registered on April 24, 2026

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Pre-Trial

Trial Information

General Information

Title

The shadow education market in Portugal: A Discrete Choice Experiment

RCT ID

AEARCTR-0018418

Initial registration date

April 19, 2026

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

April 24, 2026, 8:47 AM EDT

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

Locations

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Primary Investigator

Name

Susana Peralta

Affiliation

Nova School of Business and Economics

Contact Primary Investigator

Other Primary Investigator(s)

PI Name

PI Affiliation

PI Name

PI Affiliation

Additional Trial Information

Status

In development

Start date

2026-04-21

End date

2027-04-30

Keywords

Education

Additional Keywords

Private tutoring; Discrete choice experiment.

JEL code(s)

Secondary IDs

Prior work

This trial does not extend or rely on any prior RCTs.

Abstract

This study uses a discrete choice experiment (DCE) to investigate parental preferences in the market for private tutoring for students in upper secondary education (10th to 12th grades). Parents or legal guardians are presented with a series of hypothetical tutoring options that vary across key attributes. Each respondent completes eight choice tasks drawn from a larger experimental design of sixteen choice sets.

The DCE is implemented through an online questionnaire administered to a representative sample of the population, stratified by NUTS II regions and maternal educational. The study aims to estimate preferences for tutoring characteristics and to explore heterogeneity across households.

The results will provide insights into the determinants of demand for private tutoring and inform understanding of inequalities in access to supplementary education.

External Link(s)

Registration Citation

Citation

Freitas, Pedro , Bruno P. Carvalho and Susana Peralta. 2026. "The shadow education market in Portugal: A Discrete Choice Experiment." AEA RCT Registry. April 24. https://doi.org/10.1257/rct.18418-1.0

Sponsors & Partners

Experimental Details

Interventions

Intervention(s)

No treatment is provided. Pure DCE.

Intervention Start Date

2026-04-21

Intervention End Date

2026-07-21

Primary Outcomes

Primary Outcomes (end points)

Willingness to pay for different tutoring characteristics.

Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)

Private tutoring market size

Secondary Outcomes (explanation)

Experimental Design

The study uses a discrete choice experiment (DCE) to measure preferences for private tutoring among parents or legal guardians of students in compulsory education. In each choice task, respondents are asked to choose between hypothetical tutoring alternatives defined by a fixed number of attributes, or to select a no-tutoring option.

The experiment includes 5 attributes describing tutoring services: price, tutor experience, format of tutoring, whether the tutor is the student’s subject teacher, and proximity to home (travel time).

The experiment consists of an online survey incorporating a discrete choice experiment (DCE) designed to elicit parental preferences for private tutoring services for students in compulsory education. Respondents (parents or legal guardians) are presented with a series of hypothetical choice tasks in which they select their preferred option among alternative tutoring profiles.

Each tutoring profile is defined by a set of attributes. The experimental design comprises 16 choice sets, from which each respondent is randomly assigned 8 choice tasks to complete.

The survey is administered online to a representative sample of the population, stratified by NUTS II regions and maternal education. In addition to the choice tasks, the questionnaire collects information on household socioeconomic characteristics, current and past use of tutoring, student academic outcomes, parental aspirations and expectations, and reasons for (non-)participation in private tutoring, among other socioeconomic and educational variables.

The intervention does not manipulate real market conditions or provide actual tutoring services; it is limited to stated preference elicitation through hypothetical scenarios.

Experimental Design Details

Not available

Randomization Method

Randomization via the Qualtrics platform.

Randomization Unit

Individual. Each respondent is randomly allocated to a subset of 8 of the 16 choice sets.

When the respondent declares more than one compulsory school student in the household, the survey selects one student at random from the subset of students that attends upper secondary schooling (10th to 12th grade) and asks the subject to decide on the hypothetical private tutoring scenarios referring to the sampled student. If no student in the household attend upper secondary schooling, the survey is terminated.

Was the treatment clustered?