Request data access

We share our (meta)data

We believe that open science is important in improving science quality. Therefore, we have made our protocol and collected meta-data accessible to other researchers. Do you have a project idea and would like to collaborate? Please reach out to us
To the MetaData Explorer

Metadata & protocols

For now, you can download our protocols for the two  childhood cohorts. Later on, we will share our data for which you can request data access, see the process below.

MEtadata explorer

Explore all constructs and data in our study

The Leiden-CID study follows a multi-informant (i.e., individual, sibling and parent reports), multi-method (observation, self-report and experimental) multi-index (behavior, hormones, brain measures) approach.

We assessed eight different constructs by including more than a hundred measures in two age cohorts (early and middle child cohorts) over six annual waves of data collection. Use our metadata explorer to find out which measures were collected in which cohort, wave and age range.

Browse our metadata

And find out what constructs we measured, how and when we measured them, and which respondent took part in which measure.
To the MetaData Explorer

Make your own metadata browser

Would you like to make your own metadata browser for your own dataset? We share the code on GitHub.
Code on GitHub
In our open science endeavors transparency, findability and accessibility are key.


As you can see in the metadata explorer, we have used many different measures. The variables of the measures in these data files are not identical for every wave and for each type of respondent. To illustrate, in some waves children received different items of a questionnaire than their parent(s), and some subparts of tasks were only used in some waves but not others.

To give a clear overview of all these different measures and the exact content of the data files, we constructed a codebook in addition to our metadata explorer.
Download the LCID codebook (PDF)

Data collection protocols

Get access to our data collection protocols

Data collection in the Leiden-CID study has been a large collaborative effort. Each wave of data collection is made possible by the combined efforts of researchers, research assistants, and research interns. To ensure all participants received the same instructions throughout the wave of data collection we used extensive data collection protocols.

These protocols consist of a step-by-step run through the visit, with exact instructions for every task. In this way we could keep conditions consistent across researchers. In addition, we adapted all our instructions to be suitable for our young participants.

More about our data collection

Please note that we made the visit as efficient as possible, to reduce participants burden. Therefore, we did parallel assessments of the children and parent. Hence, multiple researchers were present during each visit, and each attending researcher followed their own protocol. As such we could limit the visit to a time frame of 2.5 - 4 hours.

After each visit participants performed some ambulatory assessments at home, including the collection of saliva samples, videotaping an evening meal for observation purposes, and measuring tympanic membrane temperature.

Parents received an extensive instruction to assist them in correctly performing the assessments. A copy of this parent instruction for the ambulatory assessments is also available.

Protocols are available in Dutch but can be made available in English upon request.

Download our protocols

You can download all the protocols (in Dutch) that we used during the Early Childhood Cohort (ECC) and Middle Childhood Cohort (MCC).

Each package contains the protocols for all years of data collection (waves), including:
  • home- and lab visit protocols for all researchers involved,
  • contact protocols,
  • video editing protocols,
  • ambulatory assessment protocols,
  • and data processing protocols.

Request access to our data

We share our data

As explained in our vision, we believe that open science is important in improving science quality. Therefore, we will make our collected data accessible to other researchers. The datasets of the L-CID project collected from 2013 to 2023 are available on the YODA platform (Coming soon). For detailed information about the datasets, please see the metadata explorer.

The metadata of the dataset are openly available, while access to the dataset itself is limited due to the sensitive nature of the research in accordance with the principles of the GDPR.

Who can get access?

All bona fide researchers that carry non-commercial, publicly-funded research can get access to our data. You fill out a data request form, which will be reviewed by the project Research Data Access Committee according to the criteria outlined in the data sharing protocol of the project. Once approval is granted, data sharing is subject to the signature of our Data Sharing Agreement.

Important remark: For researchers within the EEA where GDPR applies, access will generally be granted provided that all other conditions are met, while for researchers outside of the EEA, an additional evaluation by the privacy office will be needed.
  • Data request form

    Data Sharing Agreement


    Phase 1: Acquiring data

  • DOI preprint

    Publication package

    Phase 2: Publishing

  • DOI published article

    Archiving DRFs

    Revoking Data Access

    Phase 3: After publishing

Data request form

When a researcher requests certain data a Data Request Form must first be sent in. This DRF will be partially completed by the research team. A DRF is needed to identify specific needs and requirements, and assists in processing these requests.

The DRF template will be available soon. Requests will generally be processed within three weeks. A DRF contains the following part:

  1. Project title
  2. Primary author (name, affiliation)
  3. Other authors (name, affiliation)
  4. Project description Please briefly explain the project aim, theoretical background, hypotheses, methods and data analysis plan (300-500 words)
  5. Request status (initial data request or an addendum)
  6. Preregistration (Yes or no, because…)
  7. List of requested variables
    • State which cohort, wave, what measure and what respondents are needed. Additionally, you can explain which (random) selection of participants will be needed. Note. Clearly state from which paper you got these variables from and give them the same name.
  1.     Project planning
    • Describe the estimated project planning (i.e, preregistration available, analyses, paper ready for submission).

The completed DRF must be sent to the data manager, Simone Mulder ( with Eveline Crone in the CC (

DOI preprint

In the process of writing and publishing an article, a manuscript gets submitted to a journal for peer review. We ask researchers to share a DOI of this original manuscript (AOM), the preprint, once available.

The DOI of the preprint will then be added to our publication list.


Before you collect additional data or before you begin your analysis you have the option to preregister your research to specify your research plan in advance of your study.

Preregistering will increase result credibility and helps plan your research. Additionally, it provides a good setup for other researchers that would like to build on your research design/idea. A template for preregistration can be found on the OSF website.


In your preregistration you provide the following elements:

  1. Basic metadata (e.g. title, description, study information, etc.)
  2. Your research plan (e.g. study type, randomization, etc.)
  3. Sampling
  4. Variables
  5. Analysis plan (e.g. statistical models, data exclusion, etc.)
  6. Other information (e.g. cited literature)

For a detailed overview of the content, see the OSF website.

Data Sharing Agreement (DSA)

After the DRF is submitted and accepted, a Data Sharing Agreement (DSA) needs to be submitted. This formal contract outlines clearly what exact data (including file types) will be shared and will be set up in collaboration between both parties.


It serves to protect both the supplier and receiver of the data from misuse or other claims. Additionally, considering that both parties agreed on the data-use and -sharing, it prevents miscommunication.

A DSA consists of the following elements:

  1. Parties
    1. Who and which department provides the data?
  2. Users(s) of the data
    • Insert name, titles, department and contact information of the new users of the data.
  3. Agreement
    • List of the requested data files. This list serves as an overview and control list.The files must be stated with the correct extensions in which they are delivered (.sav, .tsv, etc.).
  4. Conditions
    • List with rules, rights and citations. These conditions list restrictions to data use and -sharing, as well as provide guidance on how recipients should proceed with findings generated from the received data.
  5. Method of data sharing
    • A clear explanation of how the research team will share the requested data. E.g. physically or electronically, encrypted or not.
  6. Period of agreement
    • Clear description of a time frame in which the recipient will be granted access to the data. This ends with how the agreement will come to an end. Will the data be destroyed or will access get revoked etc.
  7.  Costs
    • If any expenses are related to sharing the data, clarify who will cover these expenses. (recipient, sharer, shared costs?)

The DSA ends with signatures on behalf of the research team and on behalf of those that request the data.

Publication Package

To maintain an open science culture, we ask for a publication package to be shared when an article using our data gets published. This publication package should be sent to the datamanager of Leiden-CID, and will then be made semi-publicly available on Dataverse.

Benefits of publication package

This not only ensures transparency about the manner in which our data was used but is also beneficial to researchers. For example, publication packages facilitate the possibility of replicating studies since all necessary steps are documented. Additionally, when in the future questions arise about a published article (e.g., analyses), these documented steps can be easily retraced to provide answers and/or locate potential mishaps.


The publication package should include:

  1.     A published manuscript.
  2.     Used tasks and questionnaires.
  3.     Raw data.
  4.     Computer code.
  5.     Processed data files.
  6.     Supplementary information.
  7.     An approved ethics protocol.

An extensive guide on how to build your publication package will become available soon.


It is most efficient to start building the publication package as soon as the DRF gets approved. We have experienced that it takes considerably more effort to collect all necessary files after the publication than organizing the files while you are working on them. Starting later also brings risks of inaccuracy as not all steps may be remembered and files could get misplaced.

This is why we ask for the publication package to be shared within one month of the publication of the article.

DOI published article

In addition to providing us with a DOI of preregistration and the preprint, we ask researchers to send us a DOI of the published article. This can be done by adding the link to the form on the personal account on the website of Leiden-CID.

The DOI will then be added to our publication list, which makes for easier findability of the article.

Archiving DRFs

Once there is a publication available, the DRF belonging to the data used for the article will be archived. This archive will be public and can be found on this website soon.

The existence of an archive such as this one, in combination with a clear pre-registration, makes for a transparent overview of the original plan of research and the final product. This way any deviations from the plan can easily be monitored and/or reported on.

Revoking Data Access

We strive to make our data accessible to other researchers but at the same time want to protect our data and our participants' privacy. We feel that data should only be shared when it is being used.

For this reason, data access will be revoked on two occasions:

  1. After publication
    1. Two months after publication, the author will lose access to the data that was used. Additionally, an email will be sent, requesting that any data that may still be in the author's possession (e.g. when the publication package was made) will be removed.
  1. When data has not been used within two years of receiving the data.
    1. When there has been no submission or publication of an article on the data after two years, an update will be requested via email. If there are no plans and/or possibilities of using the data in the near future, data access could be revoked. However, in case of force majeure or exceptional circumstances, extension of data access can be requested.

Development matters | Leiden-CID study

This study was developed as one of four work packages of the overarching Consortium on Individual Development (CID).

CID is a large multidisciplinary collaboration that unites the best researchers on youth and development in the Netherlands.
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