Calculating with checkbox fields in EDC/CDMS

Check if a box was checked

Checkbox fields are saved as a semi-colon separated string, e.g. "1;4;5". To be able to perform calculations with these values, you will need to split the string in separate values and check if a specific value of interest is in the collection of values.

For example, to check whether a checkbox with the option value 5 was checked, you can use:

var splitted = "{variable_name}".split(';');
if (splitted.indexOf("5") > -1) {
 1;
} else {
 0;
}

This will return 1 if that option was checked or 0 if it wasn't. Replace variable_name with your own checkbox variable and '5' with your values of interest.

Retrieve the highest or lowest value of the selected checkboxes

To retrieve the highest value you can use Math.max.apply() and Math.min.apply() to retrieve the lowest value.

The below calculation will return the maximum value from the selected checkbox values.

var splitted = "{variable_name}".split(';');
Math.max.apply(null, splitted);

The below calculation will return the minimum value from the selected checkbox values.

var splitted = "{variable_name}".split(';');
Math.min.apply(null, splitted);

Calculate the sum of multiple options of a checkbox field

The below calculation will calculate the sum of multiple options of a checkbox field. 

var splitted = "{variable_name}".split(";");
var myTotal = 0; // Variable to hold your total
for(var i = 0, len = splitted.length; i < len; i++) {
 myTotal += Number(splitted[i]);
}
myTotal;

In the third line, a for loop iterates over the values of your checkbox fields that are selected.

Calculate the number of checked boxes

The below calculation will calculate the number of checked boxes:

'##allowempty##';
if("{variable_name}" == "'NA'") {
'0';
} else {
var splitted = "{variable_name}".split(";");
splitted.length;
}

Please note that "splitted.length" will always be >= 1.

Calculate if any checkbox was selected

The below calculation will calculate if any of the checkboxes have been selected.

'##allowempty##';
if ("{variable_name}" == "'NA'") {
 'Checkbox is empty'
}; 

Calculate how many checkboxes are selected and their total sum

The below calculation will calculate how many checkboxes were selected and their total sum.

var string = "{check_boxes}".split(";");
var myTotal = 0;
var sum = 0;
for (var i = 0; i < string.length; i++) {
 if (string.indexOf(string[i]) > -1) {
 myTotal = myTotal + 1;
 sum = sum + parseInt(string[i]);
 }
};
"There are " + myTotal + " selected checkboxes with a total sum of " + sum + " .";

Assign different values to checkbox options and calculate the total

All options in a checkbox option group must have a unique value. For example, 'Option A' with value 1, 'Option B' with value 2 and 'Option C' with value 3. However in some cases it is necessary to assign the same values to different options to calculate the total score. 

For example, 'Option A' with value 1, 'Option B' with value 1 and 'Option C' with value 2. Use this calculation template to assign the same values to different options and calculate their total score:

var splitted = "{checkbox_variable}".split(";");
var myTotal = 0;
if (splitted.indexOf("1") > -1) {
myTotal+=1;
}
if (splitted.indexOf("2") > -1) {
myTotal+=1;
}
if (splitted.indexOf("3") > -1) {
myTotal+=2;
}
if (splitted.indexOf("4") > -1) {
myTotal+=3;
}
if (splitted.indexOf("5") > -1) {
myTotal+=3;
}
myTotal;