Confidence Intervals
 

I noticed during the calculation of confidence intervals at multiple sets of
data that the confidence intervals obtained using the "Descriptive Analysis"
funtion under the "Data Analysis" tool pack is different than using the
CONFIDENCE function (i.e, =CONFIDENCE(alpha, SD, n). What is the difference?
How is the confidence interval calculated using the Descriptive Analysis
function?

thanks....

Confidence Intervals
 

Correction - I meant to say "Descritive Statistics" instead of "Descriptive
Analysis"

"waldoafit" wrote:

I noticed during the calculation of confidence intervals at multiple sets of
data that the confidence intervals obtained using the "Descriptive Analysis"
funtion under the "Data Analysis" tool pack is different than using the
CONFIDENCE function (i.e, =CONFIDENCE(alpha, SD, n). What is the difference?
How is the confidence interval calculated using the Descriptive Analysis
function?

thanks....

Confidence Intervals
 

waldoafit -

The CONFIDENCE function uses the normal distribution and yields the
half-width for an interval when the population standard deviation is known.

The "Confidence Level" of the Descriptive Statistics tool uses the t
distribution and yields the half-width when the standard deviation is
estimated from the sample data.

For example, if the data range is A2:A18 and you specify 90% confidence, the
tool yields

=TINV(0.1,COUNT(A2:A18)-1)*STDEV(A2:A18)/SQRT(COUNT(A2:A18))

- Mike
http://www.mikemiddleton.com

"waldoafit" wrote in message
...
I noticed during the calculation of confidence intervals at multiple sets
of
data that the confidence intervals obtained using the "Descriptive
Analysis"
funtion under the "Data Analysis" tool pack is different than using the
CONFIDENCE function (i.e, =CONFIDENCE(alpha, SD, n). What is the
difference?
How is the confidence interval calculated using the Descriptive Analysis
function?

thanks....