Basics of REDCap

REDCap defines Data Collection Instruments as "data entry forms" and "surveys".

1. With "surveys" you can collect data directly from participants. Participants will access your questions via a secure webpage. No authentication is required; however, you can enable the Survey Login feature if needed.
2. With "data entry forms", data is entered by authorized REDCap project users. REDCap log-in access and project rights are required to view and edit the data entry forms.

More information on this topic can be found in the FAQ section under the "Creating Forms and Instruments" field (subsection "Should I use a survey or data collection form?").

• For ALL projects, you must define a unique identifier as the first field on your first data entry form. The data values entered into this field must be unique. The system will not allow for duplicate entries. If you do not have a specific unique identifier, you can enable the option “Auto-numbering for records”.
• Examples of Unique Identifiers: Study-assigned ID
• Examples of Non-Unique Identifiers: Names, Dates of Birth, Consent Dates
• The unique identifier must be a 'text' field. In addition, please note that unique identifier values will be visible at the end of the URL -- and likely cached in web browsers -- as individual records are viewed or entered.
• It is strongly recommended that you do not use Protected Health Information (PHI) Identifiers such as MRN or DOB+initials as the unique identifier. This is an additional precaution to preserve research participant confidentiality from displaying in the URL and becoming cached.

• The first variable listed in your project is the unique identifier which links all your data.
• For any type of project, you must define the unique identifier field. This is the first field of the first instrument and if not using a template, the default is Record ID[record_id]. For projects where a survey is the first data collection instrument, the value must be numeric and auto-increments starting with the highest value in the project. If no records exist, it will begin with '1'.
• Users can define a unique identifier value that is not numeric (ex: Site-001) and does not auto-increment for projects with surveys: Instead of enabling the FIRST instrument as a survey, have a data collection instrument with data entry fields, then collect data via subsequent surveys.
• The secondary unique field may be defined as any field on the data collection instruments. The value for the field you specify will be displayed next to the your unique identifier when choosing an existing record/response. It will also appear at the top of the data entry page when viewing a record/response. Unlike the value of the primary unique identifier field, it will not be visible in the URL.
• The data values entered into the secondary unique field must also be unique. The system will not allow for duplicate entries and checks values entered in real time. If a duplicate value is entered, an error message will appear and the value must be changed to save/submit data entered on the data entry instrument.
• The redcap_survey_identifier is the identifier defined for surveys when utilizing the Participant Email Contact List and sending survey invitations from the system. The “Participant Identifier” is an optional field you can use to identify individual survey responses so that the participant doesn’t have to enter any identifying information into the actual survey. This field is exported in the data set; the email address of the participant is not.

The Field Type dictates how the field will be shown on the data entry form.

A longitudinal project is similar to a traditional data collection project in that multiple data entry forms are defined. However unlike the traditional model, forms in a longitudinal project can be completed repeatedly for a single record. The longitudinal model allows any data entry page to be repeated any given number of times across pre-defined time-points, which are specified by the user before data is collected. So rather than repeating a data entry form multiple times in the Data Dictionary, it can exist only once in the Data Dictionary but be repeated N number of times using the longitudinal model.

The longitudinal project lets you define “events” for your project that allow the utilization of data collection forms multiple times for any given database record. An “event” may be a temporal event in the course of your project such as a participant visit or a task to be performed. After events have been defined, you will need to designate the data entry forms that you wish to utilize for any or all events, thus allowing you to use a form for multiple events for the same database record. 

All projects when first created start in Development. In Development, you can design, build, and test your REDCap projects. All design decisions can be made in real time and are implemented immediately to your project. All survey and data entry features/functions can and should be tested.

From Development, you will move your project to Production by clicking the button on the Project Setup page. All survey and data entry features/functions will be exactly the same as they are in development with the exception of certain Project Setup features. Some project and form design updates will require contacting a REDCap Admin and/or submitting data collection instrument changes in Draft Mode. Changes to data collection instruments in Draft Mode are not made to your project in real time. After making updates, you must submit the changes for review. Review and approval time will vary and are institution specific.

• The Data Dictionary is a specifically formatted spreadsheet in CSV (comma separated values format) containing the metadata used to construct data collection instruments and fields. The changes you make with the data dictionary are not made in real time to the project (off-line method). The modified file must first be uploaded successfully before changes are committed to the project.
• The Online Designer will allow you to make create/modify/delete data collection instruments and fields (questions) very easily using your web browser. Changes are made in real time and available immediately for review and testing.
  
• The Data Dictionary in REDCap allows you to edit the questions in your project in Excel and then upload to REDCap. Everything you can do in the Online Designer, you can also do in the Data Dictionary. While it has a steeper learning curve, once you get used to it, you will be able to create forms much quicker using the data dictionary.

An example Data Dictionary can be found under the "Additional Resources" section of this page on the left side menu.

Below is a tutorial on using the Data Dictionary:

REDCap_HowTo_DataDictionary.pdf

More information on the Data Dictionary can also be found under the "Best Practices" section of this page.

Before you can set up surveys in your project, obtain a web link or send out survey invitations, you have to enable your project to support surveys and designate which forms in your project you want to act as surveys. To do this:

• Log in to redcap and open your project.
• From your project “Home Page”, use the tabs at the top to navigate to “Project Setup”.
• 

• Under “Main project settings”, the first option allows you to enable surveys in a project. NOTE: This feature is only available to users when the project is in DEVELOPMENT. Once in production, a REDCap Admin will have to enable surveys in a project.
• Once you have enabled your project to support surveys, you will need to tell REDCap which specific forms in your project you want to treat as a survey.  REDCap does not require you to make an entire project a survey-you can enable surveys on a form by form basis.
• To enable individual forms as surveys, navigate to the “Online Designer” through the “Project Setup” page. Click “Enable".
• Clicking on the “Enable” button will open a tab where you can set up your survey. Among other things, this tab contains fields that will allow you to change your survey title and the text participants see when they finish your survey, change how your survey looks by changing the theme or adding a logo, redirect participants to a URL upon completion and/or limit how long your survey is active.
• After you have gone through this page and adjusted your options, hit “Save Changes” to save your survey settings and enable your form as a survey. It is always possible to go back later and edit your survey’s settings through the Online Designer page as well.
• 

Now that you have enabled both your project and at least one form to support surveys, you will be able to set up participant lists, obtain a URL (aka web link), and manage survey participation.

• Click on "Manage Survey Participants". This is a new section that appears after at least one form in your project has been enabled for survey use.
• On this page you can Click on “Open Public Survey Link” to see your survey just as your participants will see it. We recommend entering data to make sure your survey is working the way you expect it to. When you move to production, REDCap will ask you if you wish to keep or erase your test data.
• This is also where you can obtain your survey URL. It will not change at any point once it is created.
• 

REDCap users can compile a list of participants, send invitations, track who has responded, and view a log of all invitations that have been sent. This guide, complete with screenshots, describes how to set up Survey Invitations in your project.

REDCap_HowTo_SurveyInvites.pdf

You can set up your survey invitations to be sent automatically by using Automated Invitations. Instead of adding your survey participants through the Participant List, the automated invitations can be scheduled to be sent automatically based upon specific conditions. This guide, complete with screenshots, describes how to set up Automated Survey Invitations in your project.

REDCap_HowTo_AutomatedSurveyInvites.pdf

The survey queue displays a list of all of your surveys to a participant on one page. The queue acts as a to-do list and lets the participant know which surveys have been completed and which are left to take. This guide, complete with screenshots, describes how to set up Survey Queues in your project.

REDCap_HowTo_SurveyQueue.pdf

You may enable a Survey Login page on one or more surveys that will force your survey respondents to authenticate (log in) on your surveys before they are allowed to view and complete the survey. This guide, complete with screenshots, describes how to set up Survey Logins in your project.

REDCap_HowTo_SurveyLogins.pdf

This is a table listing all existing records/responses and their status for every data collection instrument (and for a longitudinal project, for every event). When viewing this page, form-level privileges are utilized (i.e. cannot see a form's status if user does not have access to that form), and if the user belongs to a Data Access Group, they will only be able to view the records that belong to their group.Note: Since projects may now have many surveys, REDCap no longer displays the Survey Response Summary on the Project Home page.

To enter or view individual records, you can navigate to the "Data Collection" section on the left menu bar. Depending on your project type, you will see "Add or View Survey Responses", a listing of your form names, or a "Data Entry" icon. These options will navigate you to the drop down record lists so you can select or add a new record/response.

You can also use the "Data Exports, Reports and Stats" module under "Applications" to view your data. Create New Reports to search and view your project data in aggregate.

• When you click "View Report", it queries the database in real time and displays the resulting data in table format. Variables are listed in columns and individual records are displayed in rows.

• Clicking the "Stats & Charts" option within Data Exports, Reports and Stats module, displays graphical representations for all numerical and categorical variables and provides links for cleaning notable data (missing, highest, lowest values).

For more information on what the Production stage is and why it is important to move your project from the Development stage to the Production stage, see the section under FAQ's titled "Moving to Production".

To make changes after you have moved your project to Production, first download the current Data Dictionary so that you can revert to the current version, if necessary, if something goes wrong with making changes. Then, select “Enter Draft Mode” on the Online Designer or Data Dictionary page. After making your changes, you can review them by clicking on "view a detailed summary of all drafted changes" hyperlink at the top of the page.

REDCap will flag any changes that may negatively impact your data with the following critical warnings in red:

*Possible label mismatch

*Possible data loss

*Data WILL be lost

After making and reviewing changes, you can click “Submit Changes for Review.” The REDCap Administrator will review your changes to make sure there is nothing that could negatively impact data you’ve already collected. If anything is questionable or flagged as critical, you may receive an email from the Administrator with this information to confirm that you really want to make the change.

Certain changes to the structure of the database, such as deleting events in a longitudinal project can only be done by the REDCap Administrator.

Altering a database that is in Production can cause data loss and challenges to your data analysis.

If a Production database must be modified, follow these rules to protect your data:

• Do not change existing variable names, or data stored for those variables will be lost. To restore data that has been lost in this way, revert to previous variable name(s).
• Do not change existing form names via a data dictionary upload, or form completeness data will be lost. Form names may be changed within the Online Designer without data loss.
• Do not modify the codes and response options for existing dropdown, radio, or checkbox variables; or existing data will be lost or confused.

It is acceptable to add choices to a dropdown, radio, or checkbox field; however adding an option or even an entire field may present other analytical challenges. For example, if a response option is added, it is added to all instruments for all records. For records and/or study participants who have already completed the instrument, that option was not present at the time and not available for selection. Their results may not accurately reflect their situation given the updated version of the instrument/survey. One must either consider their results in light of the instrument contents at the time of data capture or one must be careful to avoid making conclusions which would be affected by the change to the instrument.

Versioning your instruments and tracking changes over time is recommended. Use the Project Revision History to confirm changes and revisions.

1.Put the project into Draft mode.

2.Add the new form to the project.

3.Reposition the new form to be first in the project

4.Make sure the first field in the new form is the same record ID form as it was before the forms were moved

5.If the new form or the form it is replacing are surveys, make sure the correct forms are enabled as surveys and correct any changes to survey settings. Remember that the first form in the project is what the public survey link will link too—if the former first form was using the public survey link, you cannot move it without changing what the public survey link moves to

6.Put the changes into production.

Branching logic is used when you need to hide a question for some responses. In the example below, the first question asks to choose an age range from one of four options. Suppose we want to ask a follow up question, but only for patients who were minors. Branching logic to the rescue!

The first step is to design all of the questions/fields that need to be asked, regardless of whether they will be hidden or not. In our example, the patient age range is the first question. We’ll then add the second question, “Was patient’s parent/guardian notified?”

Once both questions are in place, we can add branching logic to the 2nd question, since that is the one we want to hide based on the previous answer. In other words, no branching logic is needed on the first question because we want it to appear for everyone. We only need branching logic on “Was patient’s parent/guardian notified?”, which should only appear when the first option in the question above is chosen.

Using the Drag-N-Drop Builder is the simplest way to build out your branching logic if you are new to REDCAP. Click the green arrow (circled above). Then drag your option choice to the right.

Branching Logic in REDCap allows you to hide certain fields/questions depending on specific logic. This guide, complete with examples, describes how to set up Branching Logic in your project.

REDCap_HowTo_BranchingLogic.pdf

The 'Piping' feature in REDCap allows you to inject previously collected data into text on a data collection form or survey, thus providing greater precision and control over question wording. See more about piping: http://tinyurl.com/redcappiping

REDCap has the ability to make real-time calculations on data entry forms. It is recommended that 'calc' field types are not excessively utilized on REDCap data collection instruments and that they instead be used when it is necessary to know the calculated value while on that page or the following pages or when the result of the calculation affects data entry workflow.

In order for the calculated field to function, it will need to be formatted in a particular way. This is somewhat similar to constructing equations in Excel or with certain scientific calculators.

The variable names/field names used in the project's Data Dictionary can be used as variables in the equation, but you must place [ ] brackets around each variable. Please be sure that you follow the mathematical order of operations when constructing the equation or else your calculated results might end up being incorrect.

if ([my_field] <> "", [my_field], 0)

To calculate BMI (body mass index) from height and weight, you can create 'BMI' as a calculated field, as seen below. When values for height and weight are entered, REDCap will calculate the ‘BMI’ field. The data for a calculated field are saved to the database when the form is saved and can be exported just like all other fields. To create a calculated field, you will need to do two things:

1) Set the Field Type of the new field as Calculated Field in the Online Designer, or 'calc' if you are working in the data dictionary spreadsheet.

2) Provide the equation for the calculation in the Calculation Equation section of the Online Designer or the 'Choices OR Calculations' column in the data dictionary spreadsheet.

Below is an example equation for the BMI field above in which the fields named 'height' and 'weight' are used as variables.

[weight]*10000/([height]*[height]) = units in kilograms and centimeters

([weight]/([height]*[height]))*703 = units in pounds and inches

A more complex example for another calculated field might be as follows:

(([this]+525)/34)+(([this]/([that]-1000))*9.4)

You may use conditional logic (i.e. an IF/THEN/ELSE statement) by using the function:

if (CONDITION, value if condition is TRUE, value if condition is FALSE)

Note that all operands in CONDITION must be all numeric or all dates!

This construction is similar to IF statements in Microsoft Excel. Provide the condition first (e.g. [weight]=4), then give the resulting value if it is true, and lastly give the resulting value if the condition is false. For example:

if([weight] > 100, 44, 11)

In this example, if the value of the field 'weight' is greater than 100, then it will give a value of 44, but if 'weight' is less than or equal to 100, it will give 11 as the result.

IF statements may be used inside other IF statements (“nested”). For example, if you wanted to look for values above ten if the chosen color was blue, but look for values below 20 if any other color was chosen, you could use:

if([chosen_color] = "blue", if([given_value] > 10, 1, 0), if([given_value] < 20, 1, 0))

Other advanced functions (described above) may also be used inside IF statements.

Go to the "Data Exports, Reports, and Stats" application and hit the "Export Data" button in the very first report (A: All data (all records & fields)). Then follow the prompts.

You may export data for all records in a project into a single PDF file. This option is on the Data Export Tool page. The file will contain the actual page format as you would see it on the data entry page or survey and includes all data for all records for all data collection instruments.

When exporting data, the possible formats for exporting are possible:

CSV/Excel (either raw data or with labels), SPSS, SAS, R, Stata, CDISC ODM (XML)

To limit the amount of sensitive information being exported, the following measures can be taken:

• Known identifiers
  • Remove all tagged Identifier fields (tagged in Data Dictionary)
  • Hash the Record ID field (converts record name to an unrecognizable value)
    
• Free-form text
  • Removing unvalidated text fields and removing notes/essay fields
• Date and timestamp values
  • Removing all values
  • Shifting values between 0 and 364 days

The File Repository can be used for storing and retrieving project files and documents (ex: protocols, instructions, announcements). In addition, it stores all data and syntax files when data is export using the Data Export Tool.

No. The files in the File Repository cannot be sorted alphabetically or otherwise. The table headers are not clickable. The File Repository displays files in descending order by time of upload. Oldest files are at the bottom, while more recent uploads are at the top. If you have uploaded files of different formats (e.g. Word, Excel, PDF), then a dropdown box in the upper right of the table will let you additionally sort/filter the list to show only files of a certain format.

The primary purpose of the REDCap Mobile App is offline data collection. It is NOT intended to be used by participants in order to take a survey. Your project must fit one of the following scenarios:

• It is a project that needs data collected when there is no internet access available.
• It is a project that needs data collected when there is sporadic internet access.

If either of the above are true, the REDCap Mobile App is for you! This guide, complete with screenshots, describes how to set up the REDCap Mobile App in your project.

REDCap_Mobile_App_UserGuide.pdf

Adding HTML to a form/survey will result in the raw html being included in some PDF forms or any data dictionary you might make in the project. Simply copy your project once you're done and remove all of the HTML to generate clean PDF forms if needed.

• HTML tags are keywords surrounded by angle brackets: < >
• Tags come in pairs such as <example> </example>
  • The first tag is the start tag, the second tag is the end tag (written like start tag with a backslash before it)
• Tags are wrapped around text as a way of providing formatting instructions
• An example is as follows:
  • <center> This is the center text </center>

https://redcap.vanderbilt.edu/surveys/?s=u7B74tUTsa