Statistical distribution functions

Statistical distribution functions return the probabilities of occurrence of different possible outcomes for a given input variable. You can use these functions to calculate the potential values of your data points.

The three groups of statistical distribution functions described below are all implemented in Qlik Sense using the Cephes function library. For references and details on algorithms used, accuracy, and so on, see: Cephes library. The Cephes function library is used by permission.

• The probability functions calculate the probability at the point in the distribution given by the supplied value.

  • The Frequency functions are used for discrete distributions.

  • The Density functions are used for continuous functions.

• The Dist functions calculate the accumulated probability of the distribution at the point in the distribution given by the supplied value.

• The Inv functions calculate the inverse value, given the accumulated probability of the distribution.

All functions can be used in both the data load script and in chart expressions.

Use the drop-down on each function to see a brief description and the syntax of each function. Click the function name in the syntax description for further details.

ChiDist

ChiDist() returns the one-tailed probability of the chi² distribution. The chi² distribution is associated with a chi² test.

ChiDist(value, degrees_freedom)

ChiInv

ChiInv() returns the inverse of the one-tailed probability of the chi² distribution.

ChiInv(prob, degrees_freedom)

FDensity

FDensity() returns the probability of the F distribution.

FDensity(value, degrees_freedom1, degrees_freedom2)

FDist

FDist() returns the accumulated probability of the F distribution.

FDist(value, degrees_freedom1, degrees_freedom2)

FInv

FInv() returns the inverse of the accumulated probability of the F distribution.

FInv(prob, degrees_freedom1, degrees_freedom2)

NormDist

NormDist() returns the cumulative normal distribution for the specified mean and standard deviation. If mean = 0 and standard_dev = 1, the function returns the standard normal distribution.

NormDist(value, mean, standard_dev)

NormInv

 NormInv() returns the inverse of the normal cumulative distribution for the specified mean and standard deviation.

NormInv(prob, mean, standard_dev)

TDist

TDist() returns the probability for the student's t distribution where a numeric value is a calculated value of t for which the probability is to be computed.

TDist(value, degrees_freedom, tails)

TInv

TInv() returns the t value of the student's t distribution as a function of the probability and the degrees of freedom.

TInv(prob, degrees_freedom)