Table of Contents

##
How to calculate standard deviation in Excel

STDEV.S (or just STDEV) - Standard deviation of a SAMPLE,STDEV.

P (or STDEVP) - Standard deviation of a POPULATION,STDEVA - STDEVA.

S but text and logical values included (you probably donu2019t want this one),STDEVPA - STDEVA.

P but text and logicalu2026,DSTDEV and DSTDEVP - Unlikely that you want these.

,Excel has excellent help and just asking it standard deviation would have told you all of this.

To access help in Excel (and almost any other program too) just hit the F1 key.

##
Standard deviation formula for grouped data

About all you can do is pretend that for each group there is that number of observations at the mean of that group, and then calculate as usual.

##
How to calculate standard deviation from variance

#786 - COMP SCI - C++ READ DATA FROM FILE INTO ARRAY CALC MEAN VAR,Letu2019s do it!,We will be using the C++ stream extraction operator >> to read data from our input file.Note that we can test for errors - end of file, invalid input such as an alpha character Q when reading an integer - with:,while (infile >> data) {, cout > Operator to Read Int From File in C++u201d and u201cDonu2019t Use while Loop and eof() Method to Read Int From Fileu201d:,As far as writing a C++ program to calculate the mean, standard deviation and variance, we will use the program described below as a guide.

,#include ,#include ,using namespace std;,int main() {, float val[5] = {12.

5, 7.

0, 10.

0, 7.

8, 15.

5};, float sum = 0.

0, mean, variance = 0.

0, stdDeviation;, int i;, for(i = 0; i ,#include ,,// Maximum number of data values in input data file ,,#define MAX_DATA 1000 // Max data values in input data file ,,using namespace std;,,int main(void),{, int i, nData;, float fpDataValue;, float afpData[MAX_DATA];,, float fpMean, fpSumMean;, float fpVariance, fpSumVariance, fpStdDeviation;,, string strFileName = statdata.

txt; // Input data file name ,, ifstream fileStatData(strFileName);,, /* Make sure input data file can be opened.

If not were done! */,, if (!fileStatData.

is_open()), {, cerr n;,, return 1;, },, /* Read input data file into data array */,, nData = 0;,, cout > fpDataValue), {, afpData[nData] = fpDataValue;,, cout << afpData[nData] << ;,, nData++;, },, /* Close input data file */,, fileStatData.

close();,, /* Calculate mean */,, fpSumMean = 0.

0;,, for (i = 0; i < nData; i++), fpSumMean += afpData[i];,, fpMean = fpSumMean / nData;,, /* Calculate variance */,, fpSumVariance = 0.

0;,, for (i = 0; i < nData; i++), fpSumVariance += (afpData[i] - fpMean) *, (afpData[i] - fpMean);,, fpVariance = fpSumVariance / nData;,, /* Calculate standard deviation */,, fpStdDeviation = sqrt(fpVariance);,, /* Print mean, standard deviation, and variance */,, cout << nnMean: << fpMean;, cout << nStd Dev: << fpStdDeviation;, cout << nVariance: << fpVariance;,, return 0;,},/*,statdata.

txt,12.

5 7.

0 10.

0 7.

8 15.

5,,Data: 12.

5 7 10 7.

8 15.

5,,Mean: 10.

56,Std Dev: 3.

1232,Variance: 9.

7544,*/,Notice that we are using the Hungarian notation for our variable names.

I use a as in afpData[i] instead of rgfpData[i] for arrays and a2n for doubly dimensioned arrays.

,Best wishes with your computer programming study!