Random Number Generator

Command:

Math -> Random Number Generator

Random numbers showing a particular distribution are often needed in statistics. DataLab therefor offers a random number generator which can be used to create arbitrarily distributed random numbers. Apart from some important pre-defined distributions (i.e. normal distribution, t-, F-, chi-square-, and Weibull distribution) the random number generator can be set up to generate random numbers according to a user-defined function based on 10 pivot points. In addition, the generator allows to create random numbers by combining two normal distributions.

In order to generate random numbers, you first have to select the type of the distribution of the random numbers by selecting it from the box "Type of Distribution". Currently, the following distributions are available:

• Uniform Distribution
• Normal Distribution
• t-Distribution
• F-Distribution
• Chi-Square-Distribution
• Weibull Distribution
• skewed to the left
• skewed to the right
• leptocurtic
• platycurtic
• bimodal
• user defined

After the selection of the distribution type the corresponding parameters for adjusting the distrbution are displayed. The form of the distribution and the histogram of a sample of 10000 random numbers are shown in graphical form. In addition, the four most important parameters (mean, standard deviation, skewness, and kurtosis) are indicated at the bottom margin of the window.

The range of generated random numbers is controlled by the parameters "lower border" and "upper border". Random numbers beyond this range will not be created (even if the selected distribution allowed random numbers outside this range). Thus, the user should be careful to properly set up the range of random numbers.

Please be aware of the fact that there are two kinds of distributions: (1) parametric distributions (normal distribution, t-, F-, chi-square-, and Weibull distribution) which are controlled by their parameters, and (2) non-parametric distributions which always span the distribution window, no matter how the borders are set.

After setting up the required distribution, you have to click the button "Generate Random Numbers" in order to created the random numbers. The random numbers can fill one or several columns of the data matrix; individual rows cannot be filled.