Is there a function in FormCalc for Standard Deviation (Excel StdDev)

Question

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Mayank_Tiwari · Accepted Answer

You should have it. Please try again

Thanks, I checked that. SD can be calculated for sample and population. I was using the Population's formula. Now, I have used the sample's and it is working as per your expectations. Fixed Form.

For this, the following script is being used:

var rows = this.resolveNodes("tblTestData.repeatingRow[*]");
var sm=0; 
var cm=0;
for(var i=0;i<rows.length;i++)
{ if(rows.item(i).airVoids1.rawValue)
{
sm+= Math.pow(rows.item(i).airVoids1.rawValue - form1.page1.tblTestData.row2.amountMeanX.rawValue,2);
cm=cm+1;
}
}
form1.page1.tblTestData.row2.amountDeviation.rawValue = Math.sqrt(sm/(cm-1));

Mayank_Tiwari · Answer

Let's assume you have the mean stored in a variable called 'mean' and the values are in an array called 'values' of length n. Then the way to calculate SD in FormCalc is:

sum=0;
for i=0 upto n step 2 do
sum=sum + Math.pow(values[i]-mean,2);
endfor
SD = Math.sqrt(sum/(n));

in Javascript

sum=0;
for (i=0; i<n; i++)
{sum+=Math.pow(values[i]-mean,2);}
SD = Math.sqrt(sum/(n);

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