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What is a Formula variable? 

Put your algebra skills to the test!  A Formula variable is a custom variable type that allows you to carry out calculations on other variables.  Put your algebra skills to the test!  With the Formula variable, you can

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1. Navigate to Manage Study --> Variables 
   
   
2. Click '+ New Variable'. 
   
   
   
   
3. Give the variable a friendly name.  
   1. Tip! Choose something that you will remember when you are building the variable into target modifications or participant messaging and incidents. 
      
      
      
      
4. Select the arm.  If the formula variable is calculating based on other arm-specific variables, you must select that arm.  Otherwise the variable will not be available to use for the formula calculation.
   
   
5. Next select the variable type.  For this example, we want to select Formula. 
   
   
   
6. Once you select Formula, the formula field will display.   You can use the following operators, +, -, *, or / create equations using any of the following supported characters.   The formula variable supports order of operations!
   1. Supported characters: 
      1. addition: +
      2. subtraction/negation: -
      3. division: /
         
      4. multiplication: *
      5. parentheses: ( )
      6. powers: ^ (e.g., 2^3)
7. To create your formula, copy the variables exactly as listed and add any operators. 
   
   
   
   
8. Adjust rounding criteria, if needed. 
   
   
   
   
9. Click 'Save Variable' 
   
   
10. Your new variable will be listed on the Variables overview page. 
    
    

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Creating ramp-up periods from baseline value to target value: 

See Target Value Variable for step by step instructions! 

Allowing participants to choose their own goal:

See Enrollment Run-in In Variable for step by step instructions! 

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