Probability Distributions:  ZumaStat provides utilities for probability distributions that allow you to easily calculate a p value or a critical value for a t distribution, a binomial distribution, an F distribution, a chi square distribution and a normal distribution. It also provides critical values for the Studentized range distribution and has several applications for the normal distribution (e.g., calculating the proportion of scores between two z scores). You will never need a statistical table again.

Familywise Controls of Error Rates:  The classic Bonferroni method for controlling alpha levels across a set of analyses is overly conservative. Numerous modifications of the procedure have been suggested that maintain the overall alpha level at the desired magnitude but that are statistically more powerful than the traditional Bonferroni method. ZumaStat provides three such procedures, the Holm method, the Hochberg method and the False Discovery Rate method and provides the critical p values you need to implement each.

Random Assignment: ZumaStat provides a utility to generate a set of random numbers for assigning cases to experimental conditions. For example, you tell ZumaStat you have 30 cases and 3 experimental conditions and it will generate random integers between 1 and 30 into the three conditions. You will have numbered your cases from 1 to 30 and then assign the case number to the condition that ZumaStat specifies.

Random Numbers With and Without Replacement: ZumaStat has utilities that generate random numbers with or without replacement from any specified range of values.  

Matrix Operations:  ZumaStat has simple to use utilities that will calculate the determinant, inverse, trace, rank or transpose of a matrix. In addition, it will perform matrix addition, subtraction, multiplication and division.

Coefficient Alpha:  ZumaStat calculates confidence intervals for an alpha coefficient (SPSS required).  It also has a utility where you specify the correlation you expect to observe between items and the coefficient alpha that you want to achieve. The utility then tells you how many items your scale will have to consist of in order to achieve that alpha. 

Confidence Interval for Standard Deviation:  ZumaStat calculates the confidence interval for a standard deviation.

Confidence Interval for a Variance Ratio:  ZumaStat calculates a confidence interval for the ratio of two variances. This is useful for evaluating the assumption of homogeneous variances.

Regression to the Mean:  ZumaStat offers a utility that calculates the effect of regression toward the mean for analyses that adjust for pre-existing differences between experimental and control groups by statistically holding constant the pre-test scores and examining group differences in the covariate adjusted post-test scores. You enter the pretest mean for each group and the correlation between pretest and posttest scores. ZumaStat reports the covariate adjusted posttest mean difference between the two groups that will result if the intervention that occurs between the pretest and the posttest has no effect, i.e., the difference reflects regression toward the mean.

Web Sites:  ZumaStat provides links to useful websites related to statistics, including links to secondary data bases, tutoring sites, and sites on the history of statistics.

Permutations and Combinations:  ZumaStat offers utilities for calculating permutations and combinations. For example, if you have 3 questions on an interview and want to counterbalance the order in which people get the questions, how many different orders of three are there? ZumaStat can provide the answer.