Statistica has three different calculators:

1. Distributions calculator for Beta, Binomial, Cauchy, Chi-square, Exponential, Extreme value, F (Fisher), Gamma, Laplace, Lognormal, Logistic, Pareto, Poisson, Rayleigh, t (Student), Weibull, and Z (Normal)

Compute critical values for a specified distribution based on user-specified parameters, degrees of freedom, or significance levels for the distribution. Visually explore distributions. Graphs contain the density function and cumulative distribution function for the specified distribution based on user-specified parameters. What does a Poisson distribution with *Lambda = 6 *look like? What does an inverse Weibull distribution look like with *W = 1.3, p = .75, scale = 1 and shape = 1* ? Symmetric distributions can use one-tailed or two-tailed test.

2. Pearson Product Moment Correlation Coefficient (PPMCC)

Creates the p-value for a given correlation coefficient or the correlation coefficient (based on specified sample size) for a user-specified value of p. Calculator also computes the Fisher z transformation for correlation coefficients.

3. Six Sigma

Compute the standard number of defects per one million opportunities (DPMO) and the process Yield (in percent), based on a given Sigma. Sigma can also be calculated from DPMO. This tool will produce results consistent with most designated six sigma tables (e.g., see Harry and Schroeder, 2000; Pyzdek, 2001; Rath and Strong, 2000). The computations are based on a process shift of 1.5 * sigma, and the DPMO and the process Yield are computed based on a one-sided (one-tailed) criterion.

Historical Notes: The term distribution function was first introduced by von Mises, in 1919. Karl Pearson (published in 1895) established PPMCC based on earlier work by Galton.

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