## trust Interval Calculations with Microsoft Excel

April 2, 2012 § Leave a comment

Confidence intervals often give you useful insights into data sets you’re trying to best understand. A belief interval is the interval around a sample mean into which you expect the people mean to fall a distinct division of the time.

If you have a sample of size n and know the sample mean m and people proper deviation sigma (s), you can find the range into which the actual people mean will fall x% of the time. Tasteless belief levels are 90%, 95%, and 99%.

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Using the belief Function

The belief function uses the following syntax:

=Confidence (alpha,s,n)

Alpha is the point level. It equals 1 minus the belief level (expressed as a decimal). The s consulation is the proper deviation of the data set. The n consulation gives the estimate of items in the sample.

An Example belief Interval Calculation

For example, if a sample of 500 college graduates shows that they owe an average of ,000

in student loans at graduation and the people proper deviation is ,000, you can find

a 95% belief interval evaluation of the people mean estimate owed.

To do this using the belief function, enter alpha .05 as the first argument, the proper deviation 2000 as the second argument, and n 500 as the third argument. The function looks like this:

=Confidence (0.05,2000,500)

The function returns the value 175.30. So you can say with 95% belief that the population

mean is ,000 plus or minus 5.30. (Note that if you have Microsoft Excel installed on your computer, you can copy the text shown above and paste the text into an Excel cell to make the calculation on your computer.)

One final note should be made here: If the value of the people proper deviation is unknown, you can use the value of the sample proper deviation as the point evaluation of the people proper deviation.

trust Interval Calculations with Microsoft Excel

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