# _Normsdist ( z )

FileMaker implementation of NORMSDIST Excel function

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Mislav Kos Soliant Consulting http://www.soliantconsulting.com |

_Normsdist ( 4 )

_Normsdist ( 3 )

_Normsdist ( 2 )

_Normsdist ( 1 )

_Normsdist ( 0.9 )

_Normsdist ( 0.7 )

_Normsdist ( 0.3 )

_Normsdist ( 0 )

_Normsdist ( -0.5 )

_Normsdist ( -1 )

_Normsdist ( -2 )

_Normsdist ( -3 )

_Normsdist ( -4 )

_Normsdist ( -5 )

0.999968314

0.998650033

0.977249938

0.841344741

0.815939909

0.758036422

0.617911358

0.500000001

0.308537532

0.158655259

0.022750062

0.001349967

3.17E-05

2.87E-07

Compare to Excel:

0.999999713

0.999968329

0.998650102

0.977249868

0.841344746

0.815939875

0.758036348

0.617911422

0.500000000

0.308537539

0.158655254

0.022750132

0.001349898

3.17E-05

2.87E-07

Function definition: (Copy & paste into FileMaker's Edit Custom Function window)

PURPOSE:

To provide a near equivalent of the NORMSDIST Excel function.

RESULT:

The probability that the observed value of a standard normal random variable will be less than or equal to parameter z.

NOTES:

This custom function is a FileMaker implementation of the NORMSDIST function in Excel.

Caution: This custom function is ONLY AN APPROXIMATION of the Excel function;

i.e. it will calculate an approximate answer rather than the exact answer.

(Note: The same is true of the Excel function.)

The results are accurate to several decimal places, which is typically sufficient for most uses.

Also see the custom function _Normdist ( z ; mu ; sigma ).

The difference between NORMDIST and NORMSDIST:

- NORMSDIST applies to standard normal distribution.

- NORMDIST applies to any normal distribution.

- A standard normal distribution has a mean of 0 and a standard deviation of 1.

The calculation was adapted from http://www.wilmott.com/messageview.cfm?catid=8&threadid=78622.

Here are some notes on the NORMSDIST Excel function from http://support.microsoft.com/kb/827369:

- NORMSDIST(z) returns the probability that the observed value of a standard normal random variable will be less than or equal to z.

- A standard normal random variable has mean 0 and standard deviation 1 (and also variance 1 because variance = standard deviation squared).

## Comments

Note: these functions are not guaranteed or supported by BrianDunning.com. Please contact the individual developer with any questions or problems.