Calculating standard deviation of the sample not the population-Error The value entered does not match the format of the field [StdDev4]

[sarnold1]

Follow up onneed a custom calculation script to calculate standard deviation since I posted there and didn't get a response

I need to calculate the standard deviation of the sample not the population so how do I change the document JavaScript? Also, when I don't have any variation in my 10 values, I get a warning: JavaScript Window that says The value entered does not match the format of the field [StdDev4]

Here are the Document JavaScripts

Fields:

function GetField(oDoc, cField)

{

var oField = oDoc.getField(cField);

if(oField == null)

{

  app.alert("Error accessing field \"" + cField + "\"!", 1, 0)

}

return oField;

}

StdDev:

function standardDeviation(values)
{
// compute the standard deviation from an array of vlaues;
// compute the average of the vaues;
var stdDev = "";
  var avg = average(values);
  if(avg != "")
  {
// compute the squared difference of the values and the average;
  var squareDiffs = values.map(function(value){
    var diff = value - avg;
    var sqrDiff = diff * diff;
    return sqrDiff;
  });
  // average the squared differences;
  var avgSquareDiff = average(squareDiffs);
    stdDev = Math.sqrt(avgSquareDiff);
    } // end avg not null;
  return stdDev;
}

function average(data)
{
// compute the average of an array of values;
//sum the values in the array;
  var sum = data.reduce(function(sum, value){
    return sum + value;
  }, 0);
  // compute the average of the sum of the values if number of array elements is not 0;
  var avg = '';
  if(data.length > 0)
  {
  var avg = sum / data.length;
  }
  return avg;
  }

function sum(value)
{
// sum an array of values;
var Sum = value.reduce(function(Sum, value){
    return Sum + value;
  }, 0);
return Sum;
}

Custom Calculation Script:

var MyValues = new Array();

var MyFields = new Array("AdjustedResult5.1", "AdjustedResult5.2","AdjustedResult5.3", "AdjustedResult5.4", "AdjustedResult5.5", "AdjustedResult5.6", "AdjustedResult5.7", "AdjustedResult5.8", "AdjustedResult5.9", "AdjustedResult5.10" );

var oField;

var nField;

for(var i = 0; i < MyFields.length; i++)

{

nField = '';

nField = GetField(this, MyFields).valueAsString;

if(nField != "") MyValues.push(Number(nField));

}

event.value = standardDeviation(MyValues);

--------------------------------------------------------------------------------------------------------------------

I  have also tried this for the standard deviation of the sample:

var Ravg = Number(this.getField("AvgAdjResult.1.0").valueAsString); 

var Rsum = 0; 

var Rn = 0; 

for (var i=1; i<=10; i++) { 

var Rv = this.getField("AdjustedResult1."+i).valueAsString; 

if (Rv!="") { 

Rsum+=Math.pow((Number(Rv)-Ravg),2);

Rn++; 

} 

} 

if (Rn==0 || Rn==1) event.value = ""; 

else event.value = Math.sqrt(Rsum / (Rn-1));

However, I want the cell to stay blank unless there is an average calculated. Also we have low variability in our 10 replicates so the standard deviation can be zero, but I get the error mentioned above: The value entered does not match the format of the field [StdDev4] because it doesn't like to take the square root of zero. How do I make this error disappear, but the cell still have a numeric value of 0.000000?

I tried changing it to this:

var Ravg = Number(this.getField("AvgAdjResult.1.0").valueAsString);  
var Rsum = 0;  
var Rn = 0;  
for (var i=1; i<=10; i++) {  
var Rv = this.getField("AdjustedResult1."+i).valueAsString;  
if (Rv!="") {  
Rsum+=Math.pow((Number(Rv)-Ravg),2); 
Rn++;  
}  
} 

var b =  +getField("Result1.10").value; 
var c =  Rsum / (Rn-1);
if (b==0) event.value = "";  
else if (c==0) event.value = 0.000000;
else event.value = Math.sqrt (c);

but then I don't get a result at all.

Field names are shown in bold below and an example of the data is below as well

Barometric   Pressure (mm/Hg)

Result 1

Result 2

Result 3

Result 4

Result 5

Result 6

Result 7

Result 8

Result 9

Result 10

Average of Adjusted Results

Standard Deviationof Adj Results

%RSD for dry gas standard

Standard Uncertainty

Expanded Uncertainty 99%, k=3.25

UoM g/210L

mmHg

Actual

Result1.1

Result1.2

Result1.3

Result1.4

Result1.5

Result1.6

Result1.7

Result1.8

Result1.9

Result1.10

AvgAdjResult.1.0

StdDev1

RSD1

StdUnc1

ExpUnc1

UoM1

Adjusted*

AdjustedResult1.1

AdjustedResult1.2

AdjustedResult1.3

AdjustedResult1.4

AdjustedResult1.5

AdjustedResult1.6

AdjustedResult1.7

AdjustedResult1.8

AdjustedResult1.9

AdjustedResult1.10

Barometric   Pressure (mm/Hg)		Result 1	Result 2	Result 3	Result 4	Result 5	Result 6	Result 7	Result 8	Result 9	Result 10	Average of Adjusted Results	Standard Deviation of Adj Results	%RSD for dry gas standard	Standard Uncertainty	Expanded Uncertainty 99%, k=3.25	UoM g/210L
752	Actual	0.018	0.018	0.018	0.018	0.018	0.018	0.018	0.018	0.018	0.018	0.018	0.000000	0.000000	0.000000	3.447146	0.001
	Adjusted*	0.018	0.018	0.018	0.018	0.018	0.018	0.018	0.018	0.018	0.018
752	Actual	0.036	0.036	0.036	0.036	0.036	0.036	0.036	0.036	0.036	0.036	0.036	0.000000	0.000000	0.000000	3.447146	0.001
	Adjusted*	0.036	0.036	0.036	0.036	0.036	0.036	0.036	0.036	0.036	0.036
752	Actual	0.081	0.081	0.081	0.081	0.081	0.081	0.081	0.081	0.081	0.081	0.081	0.000000	0.000000	0.000000	3.447146	0.003
	Adjusted*	0.082	0.082	0.082	0.082	0.082	0.082	0.082	0.082	0.082	0.082
752	Actual	0.148	0.149	0.149	0.149	0.148	0.148	0.148	0.148	0.148	0.148	0.149	0.000488	0.327641	0.036405	3.449175	0.005
	Adjusted*	0.150	0.151	0.151	0.151	0.150	0.150	0.150	0.150	0.150	0.150
752	Actual	0.297	0.297	0.297	0.297	0.297	0.297	0.296	0.296	0.296	0.296	0.299	0.000522	0.174546	0.019394	3.447722	0.010
	Adjusted*	0.300	0.300	0.300	0.300	0.300	0.300	0.299	0.299	0.299	0.299

[try67]

This error message typically appears when you attempt to divide a value by zero and apply it to a field that is set up as Number.

You need to add checks to your code to prevent that from happening.

[gkaiseril]

And what do you expect the Standard Deviation to be for your values?

I would set the format for the field to be "None" and see what the results are. You may need to expand the width of the field to display the entire computed value. Or you could add some console.println(() statements to display the value used in the computation in Acrobat's JavaScript Console.

For some of the values used in your calculation:

N = 10

Average = 0.017999999999999995

Average square root of difference of values and average = 1.2037062152420224e-35

Standard Deviation = 3.469446951953614e-18

The average should have been 0.018 not the irrational number 0.017999999... This value as others have a very small difference from the decimal value because of the known problem in converting decimal numbers to binary numbers. One can add some rounding to reduce this error.

One could add a rounding function with the following code:

function Round(nValue, nDec)

{

return Number(util.printf("%,101." + nDec + "f", nValue));

}

And then change the custom calculation for the standard deviation to include the rounding function and suppress the result if the rounded standard deviation is zero.

// Custom Calculation Script:

var MyValues = new Array();

var MyFields = new Array("AdjustedResult5.1", "AdjustedResult5.2","AdjustedResult5.3", "AdjustedResult5.4", "AdjustedResult5.5", "AdjustedResult5.6", "AdjustedResult5.7", "AdjustedResult5.8", "AdjustedResult5.9", "AdjustedResult5.10" );

var oField;

var nField;

for(var i = 0; i < MyFields.length; i++)

{

nField = '';

nField = GetField(this, MyFields).valueAsString;

if(nField != "") MyValues.push(Number(nField));

}

event.value = Round(standardDeviation(MyValues), 3);

if(event.value == 0)

{

event.value = "";

}