Apple iWork '09 - Manual (Page 242)

CONFIDENCE
The CONFIDENCE function returns a value for creating a statistical confidence interval
for a sample from a population with a known standard deviation.
CONFIDENCE(alpha, stdev, sample-size)
 alpha: The probability that the true population value lies outside the interval.
alpha is a number value and must be greater than or equal to 1. Subtracting the
confidence interval from 1 yields the alpha.
 stdev: The standard deviation of the population. stdev is a number value and must
be greater than 0.
 sample-size: The size of the sample. sample-size is a number value and must be
greater than 0.
Usage Notes
The confidence estimate assumes that values in the sample are normally distributed. Â
Examples
=CONFIDENCE(0.05, 1, 10) returns 0.62. If the mean of the sample values is 100, then with 95%
confidence the population mean falls in the range 99.38–100.62.
=CONFIDENCE(0.1, 1, 10) returns 0.52. If the mean of the sample values is 100, then with 90%
confidence the population mean falls in the range 99.48–100.52.
=CONFIDENCE(0.05, 1, 20) returns 0.44.
=CONFIDENCE(0.05, 1, 30) returns 0.36.
=CONFIDENCE(0.05, 1, 40) returns 0.31.
Related Topics
For related functions and additional information, see:
“STDEV” on page 290
“Listing of Statistical Functions” on page 225
“Value Types” on page 36
“The Elements of Formulas” on page 15
“Using the Keyboard and Mouse to Create and Edit Formulas” on page 26
“Pasting from Examples in Help” on page 41
CORREL
The CORREL function returns the correlation between two collections using linear
regression analysis.
242 Chapter 10 Statistical Functions