Request data access

We share our (meta)data

We believe that open science is important in improving science quality. Therefore, we will make our protocol and collected (meta)data accessible to other researchers.

Study & processing 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.

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.

our vision on open science

Improving research quality through data sharing

With the digital transitions and advancements, scientists around the world are taking endeavors to improve their research through data sharing and collaboration. We are applying a number of these initiatives to the LCID project.

Some of these require specific adaptations for our project, which we will share and motivate on this platform. Moreover, our open science vision was one of the motivations for this website. We share materials, data, code and experiences for a number of reasons:

Accessible to a diverse group of researchers

We also want to make our research accessible for researchers with a variety of backgrounds, herewith appreciating diversity in training, talents and profiles. Therefore we will include tutorials on data processing and analysis that are accessible for researchers with different levels of programming expertises. We will also include practical guides that help to get access to our data and understand data collection and structure. Please let us know what you need and provide us your feedback on our discussion forum, so we can shape our tutorials in the best way.


First, we aim to be as transparent as possible by sharing all our protocols, meta-data, scripts and lessons learned. Not only does transparency help us to get peer feedback that will ultimately enhance our scientific work, transparency also facilitates reproducibility and replication.

Reducing costs and participant burden

In addition, transparency and re-use bolsters the value of the costly and time-consuming data collection. As such, this will decrease costs of novel data collection, as our protocols are fully available. Also, we will share data, with respect to the privacy of our participants. This will not only reduce financial and herewith scarce scientific resources, but even more importantly will reduce participant burden. We are above all grateful for our amazing participants that have shared so much of their time and life with us. Thus, to reach our aims, our participants including their privacy are our highest priority.

What steps do we take to reach our goals?

Increase transparency by sharing our research protocols, best practices and lessons learned.
Make our data open access (with respect to GDPR) and accessible for researchers with varying backgrounds by may 2023.
Share tutorials on data processing and analysis.
Increase findability through metadata platform that will be launched in 2023.

Discuss with us on neurostars

If you have any questions related to Leiden CID (data), you can create a post on the discussion forum of Neurostars. Neurostars is a question and answer forum for neuroscience researchers, but can also be used for other questions.

When you have questions directed at the L-CID team or general questions that other researchers might help you with, you can start a new topic using the tag ‘leidencid’.

How to ask a question on Neurostars

Create an account on Neurostars if you do not have one yet (this is free!).
Click on create a new topic (+ New Topic).
Select category: “Neuro Questions”
Add optional tag and select “leidencid”
In our open science endeavors transparency, findability and accessibility are key.

Societal impact of our work

Citizen involvement

Our ambition is that the research results of Leiden-CID are of value to improving the lives of youth. Therefore, in extension of our open science agenda for academia, we also make parts of our research accessible and transparent for society.

One of the ways we do this is by citizen involvement, where we will include children and key figures in their lives, such as parents and teachers, in different steps of the research cycle.

Using citizen involvement and citizen science, we will enrich Leiden-CID outcomes with practical knowledge and ask questions that are relevant for society today and in the future.


In addition to citizen involvement, we also have many outreach projects to foster societal impact of the Leiden-CID study. This includes science communication in which we share our research findings in different ways with societal stakeholders, such as teachers, parents and policy makers.

We believe this is an important aspect of researcher practice and as such our researchers and staff are encouraged to develop skills for outreach activities.

What steps do we take to reach our goals?

Set up education programs, policy advice, infographics, videos, interviews, presentations and podcasts.
We will involve citizens in shaping new research questions and in interpreting our research findings.
We also conduct citizen science projects, in which citizens become scientists themselves and support research by collecting data.
We also share our research findings with children, using innovative and creative ways of reaching this age group.
Get feedback from research community on discussion platform.
Active science communication throughout the project.
Coming soon!

Request access to 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. To ensure ethical and responsible use of this data, you need to adhere to the following steps.

In the future you will be able to download our data. Below you can already find the 8 steps to take for data access, when it becomes available.
  • 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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