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CONFIDENCE (Alpha,StandardDeviation,Size)

  • is alpha value which is indicating the significance level.
  • is the value of the standard deviation.
  • is the size of the sample.
    • CONFIDENCE(), returns the confidence interval for a population mean.


  • This function gives value of the confidence intervals.
  • Confidence intervals are calculated based on the standard error of a measurement.
  • It is measures the probability that a population parameter will fall between lower bound and upper bound of the values.
  • There are four steps to constructing a confidence interval.
   1. Identify a sample statistic.
   2. Select a confidence level. 
   3. Find the margin of error.
   4. Specify the confidence interval. 
  • Normally once standard error value is calculated, the confidence interval is determined by multiplying the standard error by a constant that reflects the level of significance desired, based on the normal distribution.
  • In , is the alpha value which is indicating the significance level used to find the value of the confidence level.
  • It equals , or alpha of 0.05 indicates a 95 percent confidence level.
  • This value is 1.96
  • is the standard deviation of the population for the data range.
  • is the size of the sample.
  • Confidence interval is calculated using the following formula:
  • So
  • where is the sample mean,sigma is the standard deviation.
  • This function will give the result as error when
 1. Any one of the argument is nonnumeric. 
 3. value of s is less than 1.
  • Suppose with the population of 10 for the standard deviation 3.2, with the alpha value 0.2 then, CONFIDENCE(0.2,3.2,10) =1.296839.
  • So the Confidence interval value is .


  • The syntax is to calculate CONFIDENCE in ZOS is .
    • is value of the significance level.
  • is the size of the sample.
  • For e.g., CONFIDENCE(0.2,3.1,20)
  • CONFIDENCE(0.67,8.3..10.3,51)


  1. =CONFIDENCE(0.6,4.6,20) = 0.539393789
  2. =CONFIDENCE(0.09,8.1,25) = 2.746544290
  3. =CONFIDENCE(0.001,18.8,50) = 8.74859415

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