Apple iWork '09 - Manual (Page 305)

Chapter 10 Statistical Functions 305
ZTEST
The ZTEST function returns the one-tailed probability value of the Z-test.
ZTEST(num-date-dur-set, num-date-dur, stdev)
 num-date-dur-set: A collection of values. num-date-dur-set is a collection
containing number, date, or duration values. All values must be of the same type.
 num-date-dur: A value. num-date-dur is a number value, a date/time value, or a
duration value.num-date-dur is the value to test.
 stdev: An optional value for the standard deviation of the population. stdev is a
number value and must be greater than 0.
Usage Notes
The Z-test is a statistical test which determines if the difference between a sample Â
mean and the population mean is large enough to be statistically significant. The
Z-test is used primarily with standardized testing.
If stdev is omitted, the assumed sample standard deviation is used.
Â
Example
=ZTEST({57, 75, 66, 98, 92, 80}, 70, 9) returns 0.0147281928162857.
Related Topics
For related functions and additional information, see:
“STANDARDIZE” on page 289
“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