Difference between revisions of "Documentation/How Tos/Calc: ZTEST function"
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("Calc and Excel are different") |
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:: [[Image:Calc_z_formula.png]] | :: [[Image:Calc_z_formula.png]] | ||
| − | : and returns | + | : and returns a probability based on that. |
=== Example: === | === Example: === | ||
<tt>'''ZTEST(A2:A20; 9; 2)'''</tt> | <tt>'''ZTEST(A2:A20; 9; 2)'''</tt> | ||
| − | : returns the result of a z-test on a | + | : returns the result of a z-test on a sample A2:A20 drawn from a population with known mean 9 and known standard deviation 2. |
=== See also: === | === See also: === | ||
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=== Issues: === | === Issues: === | ||
* The validity of this measure is not clear; see for example the draft ODFF standard 16May08, and that Excel has referred to this as both a one-tailed and a two-tailed test. | * The validity of this measure is not clear; see for example the draft ODFF standard 16May08, and that Excel has referred to this as both a one-tailed and a two-tailed test. | ||
| + | * Calc and Excel produce different results. Excel calculates <tt>'''1 - NORMSDIST(z)'''</tt>. It is not clear which is correct. | ||
Revision as of 08:13, 15 June 2008
ZTEST
Returns the result of a z-test.
Syntax:
ZTEST(data; μ σ)
- data is a range or array containg a random sample from a population (population assumed to have a normal distribution).
- μ is the (known) mean of the population.
- σ is the (known) standard deviation of the population. If omitted, it is estimated from the sample data by STDEV(data).
- ZTEST calculates the z statistic as
-
- and returns a probability based on that.
Example:
ZTEST(A2:A20; 9; 2)
- returns the result of a z-test on a sample A2:A20 drawn from a population with known mean 9 and known standard deviation 2.
See also:
Issues:
- The validity of this measure is not clear; see for example the draft ODFF standard 16May08, and that Excel has referred to this as both a one-tailed and a two-tailed test.
- Calc and Excel produce different results. Excel calculates 1 - NORMSDIST(z). It is not clear which is correct.
