# Manuals/calci/CONFIDENCE

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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.

## Description

- 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. 2.Suppose 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 .

## ZOS

- 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)

## Examples

- =CONFIDENCE(0.6,4.6,20) = 0.539393789
- =CONFIDENCE(0.09,8.1,25) = 2.746544290
- =CONFIDENCE(0.001,18.8,50) = 8.74859415

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## See Also

## References