1. Calculations and Branching LogicBy
J Kevan Essmyer
Acknowledgements:
J. Phil Miller (WUSM Biostatistics)
Paul Harris (Vanderbilt CTSA)
Jack Baty (WUSM REDCap Admin)
Yu Tao (WUSM REDCap Admin)

2. Overview REDCap Overview Calculations Branching Logic
Expanded Data Validation Types
Data Quality Module
External Links functionality
Data Search Tool

3. Development “Try it” and Production “Study Data” Servers
REDCap User Request forms
REDCap Project Request forms (IRB #)
Sidedoor security certificate (External Access)
Both servers are WUSM HIPAA compliant web-based data capture systems
REDCap Policy: Study data should only be collected on the Production server

4. Project Creation Flow Chart
Create Project
–Project Name, Longitudinal or Cross-Sectional/ Survey
Move to Production Status and start Data Collection
Excel Spreadsheet Or
Online Form Designer
Test Forms
Define
Study Events
(Longitudinal)
add Schedule (optional)
Data Entry
Forms
Add Users
and
Set User Rights

5. Recent Changes Hardware Software (REDCap 4.8.x)
Improved Dedicated MySQL Database server
Software (REDCap 4.8.x)
Data Query Module
New data validation types
Search Tool
External Links

6. Biostatistics Secure Domain
Public HTTPS Access
Biostatistics Secure Domain
WEB Server
File Server
REDCap Survey
Uploaded Files
MySQL Server
Authenticated Access
Data
WEB Server
Sync
WU Campus
Data Entry /Admin
MySQL Slave Server
Data Entry /Admin
Sidedoor Server
Installation Files
Host Server

7. Calculations Variable Referrence: [event_id][variable name]
Event Id obtained from events grid
Logic Statement: (if(expression),True Result,False Result)
Simple
[weight]*10000/([height]*[height])
Complex
Calculating the Mean of groups with null valid range includes zero The following equation will calculate the Mean of a list of variables
( (if(Math.abs([A])>0,[A],0)) +(if(Math.abs([B])>0,[B],0)) +(if(Math.abs([C])>0,[C],0)) ) / ( (if(Math.abs([A])>0,1,if([A]=0,1,0)) +if(Math.abs([B])>0,1,if([B]=0,1,0)) +if(Math.abs([C])>0,1,if([C]=0,1,0)) )

8. Built in Functions DATEDIFF F(x) Units Date Formats
Type of calculation
Notes / examples
round(number,decimal places)
Round
roundup(number,decimal places)
Round Up
rounddown(number,decimal places)
Round Down
sqrt(number)
Square Root
(number)^(exponent)
Exponents
abs(number)
Absolute Value
min(number,number,...)
Minimum
max(number,number,...)
Maximum
mean(number,number,...)
Mean
median(number,number,...)
Median
sum(number,number,...)
Sum
stdev(number,number,...)
Standard Deviation
datediff([date1], [date2], "units", "dateformat", returnSignedValue)
datediff([dob],[date_enrolled],"d")
datediff([dob]," ","h","mdy",true)
Units
"y"
years
1 year = days
"M"
months
1 month = days
"d"
days
"h"
hours
"m"
minutes
"s"
seconds
"ymd"
Y-M-D (default)
"mdy"
M-D-Y
"dmy"
D-M-Y
Date Formats

9. Javascript Math Library
Math.abs(a) // the absolute value of a
Math.acos(a) // arc cosine of a
Math.asin(a) // arc sine of a
Math.atan(a) // arc tangent of a
Math.atan2(a,b) // arc tangent of a/b
Math.ceil(a) // integer closest to a and not less than a
Math.cos(a) // cosine of a
Math.exp(a) // exponent of a (Math.E to the power a)
Math.floor(a) // integer closest to a, not greater than a
Math.log(a) // log of a base e
Math.max(a,b) // the maximum of a and b
Math.min(a,b) // the minimum of a and b
Math.pow(a,b) // a to the power b
Math.random() // pseudorandom number 0 to 1
Math.round(a) // integer closest to a
Math.sin(a) // sine of a
Math.sqrt(a) // square root of a
Math.tan(a) // tangent of a

10. Pitfalls of Calculations
Changes made to equations after the start of data collection
Correct new calculated value will display on page load
Each form must be individually submitted to re-apply calculation
Calculations should be considered a tool not data.
Calculation should be reapplied during data analysis.
Multiple calculations on a form.
Order of execution is determined by the alphabetical ordering of it’s associated variable/field name.
Calculation 1 [weight_met] =[weight]*
Calculation 2 [BMI]=[weight_met]/([height]^2)
!!!Calculation 2 will occur before calculation 1
Calculate BMI in one step (Best Solution) or
Rename variable to change order (only other option)

11. Branching Logic Exposes form question if logic expression is true
[Event Id][Variable Name] = "0"
Checkboxes Format
[Event Id][variablename(code)]
To check the value of the checkboxes:
'1' = checked
'0' = unchecked
[race(2)] = "1"
[sex] = "0"
display question if sex = female; Female is coded as 0, Female
[sex] = "0" and [given_birth] = "1"
display question if sex = female and given birth = yes; Yes is codesd as 1, Yes
([height] >= 170 or [weight] < 65) and [sex] = "1"
display question if (height is greater than or equal to 170 OR weight is less than 65) AND sex = male; Male is coded as 1, Male
[last_name] <> ""
display question if last name is not null (aka if last name field is empty)

12. Online Designer

13. Branching Logic Calculation with in branching logic
[kwdays] > (10+1)
Prevent deletion of
With existing logic
(other logic statements) or <>"“
Stand alone
<>""

14. Branching logic warning about hiding existing data
Can be a dangerous situation and is best avoided.

15. Expanded Field Validation Types

16. Data Quality Module (data queries)

17. Results

18. Data Quality Module (data queries)

19. External Links Embed hyperlinks in the REDCap project menu.
Websites, Other REDCap Projects, web tools

20. Data Search Tool

21. “?!!?” Branching Logic Data Validation User Rights API Data Dictionary
Scheduling
Data Dictionary

22. REDCap Lifelines Built-in tutorial videos
Built-in Frequently Asked Question (FAQ) guide
Demonstration Databases (Some Online, more to come)
WUSM Biostat REDCap Help Queue
Monitored by 4 to 5 Administrators

23. REDCap Support

24. REDCap Goals Questions? Easy to use Metadata Driven Adaptable Features
Data entry validation
Self service tool
Questions?