The FDIST() function calculates a F probability distribution describing the variance of two data samples. The syntax for the function is FDIST (x, degrees_freedom1, degrees_freedom2). The arguments "x, degress_feeedom1, degrees_freedom2" must be numerical values toherwize the function will return the #VALUE error value. In addition if if the "x" value is negative the function will return a #NUM error value. The "x" argument is the value that FDIST is to be evaluated for, with the terms "degrees_freedom1" and "degrees_freedom2" the numerator and in the statistical function that forms the distribution. The degree of freedom of a variable relates the number of it's known variables to the number of unknown variables. The higher the degree of freedom the greater the probable variance in the resuiting sample value. The FDIST function compiles a probability distribution by using the degree_freedom 1 and degreefreedom2 and them finds the probability of a specific value occuring "x" on the probability distribution curve returning a single value. The probability density of the x value is the probability that the number x has the same variance as another number in a dstribution. The exact shape of the probabiliuty distribution depends on the value and the relative values of the degrees of freedom arguments. The shape of the probability in turn defines the probability density value for any given argument "x". The return value for the FDIST function is found by placing x on the probability distribution and finding the corrosponding probability density value. [chart] A 1/1 ratio in the degrees of freedom yield a sharp probability distribution with little variance idicating that there can be little chance of difference between values in two population distributions. [chart] A 1/10 ratio in the degrees of freedom flatterns and shifts the probability distribution towards higher x values. [chart] A 10/10 ratio in the degrees of freedom shifts the probability towards the right and widens the distribution but still maintains a high peaked probability distribution. Each of these distributions describe the probability of two populations of data with specified relative degrees of freedom having the same x value in a distribution. This makes the FDIST function an excellent tool for comparing the variability of two data distributions and conclude weather the differences are significant. For eample: Determining weather the variablity between test scores of weomen and men entering university is different or weather the variation is within the limits of expected random fluctuations. To learn more about F Distribution in statistics see: [The F Distribution Mathematics Knowledgebase] [The CHIDIST function knowledgebase]

How to use the FDIST() function: Type " =FDIST( " Enter the reference for the "x" data value "A5". Type a comma. Enter the refernce for the "degrees_freedom1" data cell "A2". Type a comma. Enter the reference for the "degrees_freedom2" data cell "B2". Type")" then press the "Enter" key.

Note: Arguments that are text that cannot be translated into numerical values or that contain errors will cause the function to return an error value. How to use the FDIST() function to create a F distribution chart: Type " =FDIST( " Enter the reference for the "x" data value "A5". Type a comma. Enter the refernce for the "degrees_freedom1" data cell "A2". Type a comma. Enter the reference for the "degrees_freedom2" data cell "B2". Type")" then press the "Enter" key.  Select the cells "A5:A15". Press the "F2" key then hold down "Ctrl" and "Shift" and press the "Enter" key.   Note: If the "degrees_freedom1" value is less than one and the "degrees_freedom2" value is more than 10 billion or if the "degrees_freedom2" is less than one and the "degrees_freedom1" is more than a billion the FDIST function will return the #NUM error value as it cannot calcualate the proability distribution to that level of detail.