Brian Dunning's FileMaker Custom Functions

HypGeomDist ( sampleSuccesses ; sampleSize ; populationSuccesses ; ... )

Returns the hypergeometric probability distribution of obtaining the number of successes in a sample, based on the success rate of the general population. Given the overall failure rate of a production line, HypGeomDist can calculate the probability of 3 items being defective in a shipment containing 100 items.

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Michael Horak   Michael Horak
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  Sample input:
HypGeomDist ( 1 ; 4 ; 8 ; 20 ; 0 )
HypGeomDist ( 1 ; 4 ; 8 ; 20 ; 1 )
  Sample output:
0.3632610939112487
0.4654282765737874

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

Returns the hypergeometric probability distribution of obtaining the number of successes in a sample, based on the success rate of the general population. Given the overall failure rate of a production line, HypGeomDist can calculate the probability of 3 items being defective in a shipment containing 100 items.

Depending on the cumulative parameter, the HypGeomDist function returns either the individual probability of obtaining exactly the number of successes, or the cumulative probability of obtaining at most the number of successes.

The HypGeomDist function parameters are:
sampleSuccesses - the number of successes in the sample;
sampleSize - the size of the sample;
populationSuccesses - the number of successes in the population;
populationSize - the size of the population ;
cumulative - a logical value that determines the form of the function: if cumulative is TRUE, HypGeomDist returns the cumulative probability of obtaining at most the number of successes; if FALSE, it returns the probability of obtaining exactly the number of successes.

Example:
A box of chocolates contains 20 pieces. Eight pieces contain a hazelnut. If a person selects 4 pieces at random, the probability of exactly 1 piece containing a hazelnut is:
HypGeomDist ( 1 ; 4 ; 8 ; 20 ; 0 ) = 36.33%

The probability of 1 piece or less containing a hazelnut is:
HypGeomDist ( 1 ; 4 ; 8 ; 20 ; 1 ) = 46.54%

 

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