


Free Statistics Calculators!

Welcome to version 3.0 of the Free Statistics Calculators website! These statistics
calculators are free to be used by anyone in the research community at large. They
are offered humbly in the hope that they will contribute in some small way to the
advancement of science and the betterment of mankind. I hope you find them useful!
The statistics calculators are organized into the 29 categories shown below. Clicking
on a category name will display a list of calculators available for that category.



 Analysis of Variance (ANOVA) Calculator  OneWay ANOVA from Summary Data This calculator will generate a complete oneway analysis of variance (ANOVA) table for up to 10 groups, including sums of squares, degrees of freedom, mean squares, and F and pvalues, given the mean, standard deviation, and number of subjects in each group. 
 Analysis of Variance (ANOVA) Intraclass Correlation Calculator This calculator will compute the intraclass correlation for an analysis of variance (ANOVA) study, given the betweengroups mean square, the withingroups mean square, and the number of subjects in each group. 
 Binomial Coefficient Calculator This calculator will compute the value of a binomial coefficient, given values of the first nonnegative integer n, and the second nonnegative integer k. 
 Binomial Probability Calculator This calculator will compute the probability of an individual binomial outcome (i.e., a binomial probability), given the number of successes, the number of trials, and the probability of a successful outcome occurring. 
 Binomial Probability Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for a binomial probability, given the number of successes and the total number of trials. This calculator relies on the ClopperPearson (exact) method. 
 Cumulative Binomial Probability Calculator This calculator will compute cumulative probabilities for a binomial outcome, given the number of successes, the number of trials, and the probability of a successful outcome occurring. For the number of successes x, the calculator will return P(Xx), and P(X>=x). 
 Cumulative Distribution Function (CDF) Calculator for the Binomial Distribution This calculator will compute the cumulative distribution function (CDF) for the binomial distribution, given the number of successes, the number of trials, and the probability of a successful outcome occurring. 
 Expected Value Calculator for a Binomial Random Variable This calculator will tell you the expected value for a binomial random variable, given the number of trials and the probability of success. 
 Probability Mass Function (PMF) Calculator for the Binomial Distribution This calculator will compute the probability mass function (PMF) for the binomial distribution, given the number of successes, the number of trials, and the probability of a successful outcome occurring. 
 Variance Calculator for a Binomial Random Variable This calculator will tell you the variance for a binomial random variable, given the number of trials and the probability of success. 
 Binomial Probability Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for a binomial probability, given the number of successes and the total number of trials. This calculator relies on the ClopperPearson (exact) method. 
 Confidence Interval Calculator for a Predicted Value of a Regression Equation This calculator will compute the 99%, 95%, and 90% confidence intervals for a predicted value of a regression equation, given a predicted value of the dependent variable, the standard error of the estimate, the number of predictors in the model, and the total sample size. 
 Confidence Interval Calculator for the Population Mean This calculator will compute the 99%, 95%, and 90% confidence intervals for the mean of a normal population, given the sample mean, the sample size, and the sample standard deviation. 
 Confidence Interval Calculator for the Population Mean (when population std dev is known) This calculator will compute the 99%, 95%, and 90% confidence intervals for the mean of a normal population when the population standard deviation is known, given the sample mean, the sample size, and the population standard deviation. 
 fsquare Effect Size Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for the fsquare effect size associated with a multiple regression study, given the fsquare value, the number of predictors in the model, and the total sample size. 
 Indirect Mediation Effect Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for an indirect mediation effect, given the regression coefficient and standard error for the relationship between the independent variable and the mediator, and the regression coefficient and standard error for the relationship between the mediator and the dependent variable. 
 Poisson Confidence Interval Calculator This calculator will compute the exact 99%, 95%, and 90% confidence intervals for a Poisson mean, given the number of event occurrences. 
 Rsquare Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for an Rsquare value (i.e., a squared multiple correlation), given the value of the Rsquare, the number of predictors in the model, and the total sample size. 
 Regression Coefficient Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for a regression coefficient, given the value of the regression coefficient, the standard error of the regression coefficient, the number of predictors in the model, and the total sample size. 
 Regression Intercept Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for a regression intercept (i.e., the regression constant), given the value of the regression intercept, the standard error of the regression intercept, the number of predictors in the model, and the total sample size. 
 Analysis of Variance (ANOVA) Intraclass Correlation Calculator This calculator will compute the intraclass correlation for an analysis of variance (ANOVA) study, given the betweengroups mean square, the withingroups mean square, and the number of subjects in each group. 
 Correlation Coefficient Calculator (from a Covariance) This calculator will compute the Pearson correlation coefficient r for two variables X and Y, given the covariance value between the two variables, and their standard deviations. 
 Covariance Calculator (from a Correlation Coefficient) This calculator will compute the covariance between two variables X and Y, given the Pearson correlation coefficient for the two variables, and their standard deviations. 
 pValue Calculator for Correlation Coefficients This calculator will tell you the significance (both onetailed and twotailed probability values) of a Pearson correlation coefficient, given the correlation value r, and the sample size. 
 Significance of the Difference between Two Correlations Calculator This calculator will determine whether two correlation coefficients are significantly different from each other, given the two correlation coefficients and their associated sample sizes. Values returned from the calculator include the probability value and the zscore for the significance test. A probability value of less than 0.05 indicates that the two correlation coefficients are significantly different from each other. 
 tValue Calculator for Correlation Coefficients This calculator will tell you the tvalue and degrees of freedom associated with a Pearson correlation coefficient, given the correlation value r, and the sample size. 
 Cumulative Distribution Function (CDF) Calculator for the Beta Distribution This calculator will compute the cumulative distribution function (CDF) for the beta distribution (i.e., the area under the beta distribution from 0 to x), given values of the shape parameters, and the point at which to evaluate the function. 
 Cumulative Distribution Function (CDF) Calculator for the Binomial Distribution This calculator will compute the cumulative distribution function (CDF) for the binomial distribution, given the number of successes, the number of trials, and the probability of a successful outcome occurring. 
 Cumulative Distribution Function (CDF) Calculator for the ChiSquare Distribution This calculator will compute the cumulative distribution function (CDF) for the Chisquare distribution, given the point at which to evaluate the function x, and the degrees of freedom. 
 Cumulative Distribution Function (CDF) Calculator for the FDistribution This calculator will compute the cumulative distribution function (CDF) for the Fisher Fdistribution (i.e., the area under the Fdistribution from 0 to x), given the numerator and denominator degrees of freedom, and the upper limit of integration x. 
 Cumulative Distribution Function (CDF) Calculator for the Noncentral FDistribution This calculator will compute the cumulative distribution function (CDF) for the noncentral Fdistribution, given an Fvalue, the numerator and denominator degrees of freedom, and the noncentrality parameter. 
 Cumulative Distribution Function (CDF) Calculator for the Noncentral tDistribution This calculator will compute the cumulative distribution function (CDF) for the noncentral tdistribution (i.e., the area under the noncentral tdistribution from negative infinity to t), given a tvalue, the degrees of freedom, and the value of the noncentrality parameter. 
 Cumulative Distribution Function (CDF) Calculator for the Normal Distribution This calculator will compute the cumulative distribution function (CDF) for the normal distribution (i.e., the area under the normal distribution from negative infinity to x), given the upper limit of integration x, the mean, and the standard deviation. 
 Cumulative Distribution Function (CDF) Calculator for the Poisson Distribution This calculator will compute the cumulative distribution function (CDF) for the Poisson distribution, given the number of event occurrences and the expected number of event occurrences. 
 Cumulative Distribution Function (CDF) Calculator for the Standard Normal Distribution This calculator will compute the cumulative distribution function (CDF) for the standard normal distribution (i.e., the area under the standard normal distribution from negative infinity to x), given the upper limit of integration x. 
 Cumulative Distribution Function (CDF) Calculator for the tDistribution This calculator will compute the cumulative distribution function (CDF) for Student's tdistribution (i.e., the area under the tdistribution from negative infinity to t), given a tvalue and the degrees of freedom. 
 Cumulative Distribution Function (CDF) Calculator for the Uniform Distribution This calculator will compute the cumulative distribution function (CDF) for the (continuous) uniform distribution, given the values of the upper and lower boundaries of the distribution and the point at which to evaluate the function. 
 Effect Size (Cohen's d) Calculator for a Student tTest This calculator will tell you the (twotailed) effect size for a Student ttest (i.e., Cohen's d), given the mean and standard deviation for two independent samples of equal size. 
 Effect Size Calculator for Hierarchical Multiple Regression This calculator will tell you the effect size for a hierarchical multiple regression study (Cohen's fsquare), given an Rsquare value for a set of independent variables A, and an Rsquare value for the sum of A and another set of independent variables B. The value returned by the calculator is the effect size attributable to the addition of set B to the model. 
 Effect Size Calculator for Multiple Regression This calculator will tell you the effect size for a multiple regression study (i.e., Cohen's fsquare), given a value of Rsquare. 
 fsquare Effect Size Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for the fsquare effect size associated with a multiple regression study, given the fsquare value, the number of predictors in the model, and the total sample size. 
 Rsquare Calculator (from an fsquare Effect Size) This calculator will compute an Rsquare value for a multiple regression model, given Cohen's fsquare effect size for the model. 
 Complementary Probability Calculator This calculator will compute the probability that event A will not occur (i.e., the complementary probability of A), given the probability of event A occurring. 
 Conditional Probability Calculator This calculator will compute the probability of event A occurring, given that event B has occurred (i.e., the conditional probability of A), given the joint probability of events A and B, and the probability of event B. 
 Joint Probability Calculator This calculator will compute the probability of two events A and B occurring together (i.e., the joint probability of A and B), given the conditional probability of event A, and the probability of event B. 
 Union Probability Calculator This calculator will compute the probability of event A or event B occurring (i.e., the union probability for A and B), given the probability of event A, the probability of event B, and the joint probability of events A and B. 
 Critical Fvalue Calculator This calculator will tell you the critical value of the Fdistribution, given the probability level, the numerator degrees of freedom, and the denominator degrees of freedom. 
 Cumulative Distribution Function (CDF) Calculator for the FDistribution This calculator will compute the cumulative distribution function (CDF) for the Fisher Fdistribution (i.e., the area under the Fdistribution from 0 to x), given the numerator and denominator degrees of freedom, and the upper limit of integration x. 
 Cumulative Distribution Function (CDF) Calculator for the Noncentral FDistribution This calculator will compute the cumulative distribution function (CDF) for the noncentral Fdistribution, given an Fvalue, the numerator and denominator degrees of freedom, and the noncentrality parameter. 
 Expected Value Calculator for an FDistribution Random Variable This calculator will tell you the expected value (i.e., the mean) for an Fdistribution random variable, given the denominator degrees of freedom. 
 FValue and pValue Calculator for Multiple Regression This calculator will tell you the Fisher Fvalue for a multiple regression study and its associated probability level (pvalue), given the model Rsquare, the number of predictors in the model, and the total sample size. 
 FValue Calculator for Hierarchical Multiple Regression This calculator will tell you the Fvalue for a hierarchical multiple regression study, given an Rsquare value for a set of independent variables A, an Rsquare value for the sum of A and another set of independent variables B, the number of predictors in A, the number of predictors in B, and the total sample size. The value returned by the calculator is the the Fvalue associated with the addition of B to the model. 
 pValue Calculator for an FTest This calculator will tell you the probability value of an Ftest, given the Fvalue, numerator degrees of freedom, and denominator degrees of freedom. 
 Probability Density Function (PDF) Calculator for the FDistribution This calculator will compute the probability density function (PDF) for the Fisher Fdistribution, given the numerator and denominator degrees of freedom, and the point at which to evaluate the function x. 
 Variance Calculator for an FDistribution Random Variable This calculator will tell you the variance for an Fdistribution random variable, given the numerator and denominator degrees of freedom. 
 Apriori Sample Size Calculator for Hierarchical Multiple Regression This calculator will tell you the minimum sample size required for a hierarchical multiple regression analysis; i.e., the minimum sample size required for a significance test of the addition of a set of independent variables B to the model, over and above another set of independent variables A. The value returned by the calculator is the minimum sample size required to detect an effect of the specified size, probability level, and power level for the addition of set B to the model. 
 Beta (Type II Error Rate) Calculator for Hierarchical Multiple Regression This calculator will tell you the beta level (the Type II error rate) for a hierarchical regression analysis; i.e., the beta level for a significance test of the addition of a set of independent variables B to the hierarchical model, over and above another set of independent variables A. The value returned by the calculator is the beta level (i.e., the Type II error rate) for the addition of the set of independent variables B to the overall hierarchical model. 
 Effect Size Calculator for Hierarchical Multiple Regression This calculator will tell you the effect size for a hierarchical multiple regression study (Cohen's fsquare), given an Rsquare value for a set of independent variables A, and an Rsquare value for the sum of A and another set of independent variables B. The value returned by the calculator is the effect size attributable to the addition of set B to the model. 
 FValue Calculator for Hierarchical Multiple Regression This calculator will tell you the Fvalue for a hierarchical multiple regression study, given an Rsquare value for a set of independent variables A, an Rsquare value for the sum of A and another set of independent variables B, the number of predictors in A, the number of predictors in B, and the total sample size. The value returned by the calculator is the the Fvalue associated with the addition of B to the model. 
 Posthoc Statistical Power Calculator for Hierarchical Multiple Regression This calculator will tell you the observed power for a hierarchical regression analysis; i.e., the observed power for a significance test of the addition of a set of independent variables B to the hierarchical model, over and above another set of independent variables A. The value returned by the calculator is the observed power for the addition of the set of independent variables B to the overall hierarchical model. 
 Indirect Effect Calculator for Mediation Models This calculator will compute the indirect effect of a mediation model, given the regression coefficient between the independent variable and the mediator variable and the regression coefficient between the mediator variable and the dependent variable. 
 Indirect Mediation Effect Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for an indirect mediation effect, given the regression coefficient and standard error for the relationship between the independent variable and the mediator, and the regression coefficient and standard error for the relationship between the mediator and the dependent variable. 
 Sobel Test Calculator for the Significance of Mediation This calculator uses the Sobel test to tell you whether a mediator variable significantly carries the influence of an independent variable to a dependent variable; i.e., whether the indirect effect of the independent variable on the dependent variable through the mediator variable is significant. This calculator returns the Sobel test statistic, and both onetailed and twotailed probability values. 
 Total Effect Calculator for Mediation Models This calculator will compute the total effect of a mediation model, given the regression coefficient between the independent variable and the mediator variable, the regression coefficient between the mediator variable and the dependent variable, and the regression coefficient between the independent variable and the dependent variable. 
 Variance Calculator for an Indirect Mediation Effect This calculator uses Sobel's multivariate delta method to compute the variance of an indirect effect in a mediation model, given the regression coefficient and standard error for the relationship between the independent variable and the mediator, and the regression coefficient and standard error for the relationship between the mediator and the dependent variable. 
 Adjusted Rsquare Calculator (Population Rsquare) This calculator will compute an adjusted Rsquare value (i.e., the population squared multiple correlation), given an observed (sample) Rsquare, the number of predictors in the model, and the total sample size. 
 Coefficient of Variation Calculator This calculator will compute the coefficient of variation for a set of data, given the standard deviation and the mean. 
 Factorial Calculator This calculator will compute the factorial for any nonnegative integer value between 0 and 2,000. 
 Zscore Calculator This calculator will compute a Zscore (i.e., a standard normal score), given an unstandardized raw value, the population mean, and the standard deviation of the population to which the unstandardized value belongs. 
 Cumulative Distribution Function (CDF) Calculator for the Noncentral FDistribution This calculator will compute the cumulative distribution function (CDF) for the noncentral Fdistribution, given an Fvalue, the numerator and denominator degrees of freedom, and the noncentrality parameter. 
 Cumulative Distribution Function (CDF) Calculator for the Noncentral tDistribution This calculator will compute the cumulative distribution function (CDF) for the noncentral tdistribution (i.e., the area under the noncentral tdistribution from negative infinity to t), given a tvalue, the degrees of freedom, and the value of the noncentrality parameter. 
 Probability Density Function (PDF) Calculator for the Noncentral tDistribution This calculator will compute the probability density function (PDF) for the noncentral tdistribution, given a tvalue, the degrees of freedom, and the value of the noncentrality parameter. 
 Confidence Interval Calculator for the Population Mean This calculator will compute the 99%, 95%, and 90% confidence intervals for the mean of a normal population, given the sample mean, the sample size, and the sample standard deviation. 
 Confidence Interval Calculator for the Population Mean (when population std dev is known) This calculator will compute the 99%, 95%, and 90% confidence intervals for the mean of a normal population when the population standard deviation is known, given the sample mean, the sample size, and the population standard deviation. 
 Cumulative Area Under the Standard Normal Curve Calculator This calculator will tell you the cumulative area under the standard normal distribution, given a zscore (i.e., the cumulative probability from minus infinity to the zscore). 
 Cumulative Distribution Function (CDF) Calculator for the Normal Distribution This calculator will compute the cumulative distribution function (CDF) for the normal distribution (i.e., the area under the normal distribution from negative infinity to x), given the upper limit of integration x, the mean, and the standard deviation. 
 Cumulative Distribution Function (CDF) Calculator for the Standard Normal Distribution This calculator will compute the cumulative distribution function (CDF) for the standard normal distribution (i.e., the area under the standard normal distribution from negative infinity to x), given the upper limit of integration x. 
 OneTailed Area Under the Standard Normal Distribution Calculator This calculator will tell you the onetailed (righttail) area under the standard normal curve, given a Zscore (i.e., the onetailed probability from the zscore to positive infinity). 
 Probability Density Function (PDF) Calculator for the Normal Distribution This calculator will compute the probability density function (PDF) for the normal distribution, given the mean, standard deviation, and the point at which to evaluate the function x. 
 Probability Density Function (PDF) Calculator for the Standard Normal Distribution This calculator will compute the probability density function (PDF) for the standard normal distribution, given the point at which to evaluate the function x. 
 Standard Normal Distribution ZScore Calculator This calculator will tell you the normal distribution Zscore associated with a given cumulative probability level. 
 TwoTailed Area Under the Standard Normal Distribution Calculator This calculator will tell you the twotailed area under the standard normal curve, given a Zscore (i.e., the twotailed probability from +/ the Zscore to infinity on both tails of the distribution). 
 Zscore Calculator This calculator will compute a Zscore (i.e., a standard normal score), given an unstandardized raw value, the population mean, and the standard deviation of the population to which the unstandardized value belongs. 
 Cumulative Distribution Function (CDF) Calculator for the Poisson Distribution This calculator will compute the cumulative distribution function (CDF) for the Poisson distribution, given the number of event occurrences and the expected number of event occurrences. 
 Cumulative Poisson Probability Calculator This calculator will compute cumulative probabilities for a Poisson outcome, given the total number of events observed, the expected number of events per interval, and the total number of intervals. For the total number of events observed k, the calculator will return P(Kk), and P(K>=k). 
 Poisson Confidence Interval Calculator This calculator will compute the exact 99%, 95%, and 90% confidence intervals for a Poisson mean, given the number of event occurrences. 
 Poisson Probability Calculator This calculator will compute a Poisson probability (i.e., the probability of a specific number of events occurring within a specific number of fixed intervals of time or space), given the total number of events observed, the expected number of events per interval, and the total number of intervals. 
 Probability Mass Function (PMF) Calculator for the Poisson Distribution This calculator will compute the probability mass function (PMF) for the Poisson distribution, given the number of event occurrences and the expected number of event occurrences. 
 Binomial Probability Calculator This calculator will compute the probability of an individual binomial outcome (i.e., a binomial probability), given the number of successes, the number of trials, and the probability of a successful outcome occurring. 
 Complementary Probability Calculator This calculator will compute the probability that event A will not occur (i.e., the complementary probability of A), given the probability of event A occurring. 
 Conditional Probability Calculator This calculator will compute the probability of event A occurring, given that event B has occurred (i.e., the conditional probability of A), given the joint probability of events A and B, and the probability of event B. 
 Cumulative Area Under the Standard Normal Curve Calculator This calculator will tell you the cumulative area under the standard normal distribution, given a zscore (i.e., the cumulative probability from minus infinity to the zscore). 
 Cumulative Binomial Probability Calculator This calculator will compute cumulative probabilities for a binomial outcome, given the number of successes, the number of trials, and the probability of a successful outcome occurring. For the number of successes x, the calculator will return P(Xx), and P(X>=x). 
 Cumulative Poisson Probability Calculator This calculator will compute cumulative probabilities for a Poisson outcome, given the total number of events observed, the expected number of events per interval, and the total number of intervals. For the total number of events observed k, the calculator will return P(Kk), and P(K>=k). 
 FValue and pValue Calculator for Multiple Regression This calculator will tell you the Fisher Fvalue for a multiple regression study and its associated probability level (pvalue), given the model Rsquare, the number of predictors in the model, and the total sample size. 
 Fisher's Exact Test Calculator for a 2x2 Contingency Table This calculator will compute both the exact hypergeometric probability and the exact twotailed probability of obtaining a distribution of values in a 2x2 contingency table using Fisher's exact test, given the number of observations in each cell. 
 Fisher's Exact Test Calculator for a 2x3 Contingency Table This calculator uses the FreemanHalton extension of Fisher's exact test to compute the (twotailed) probability of obtaining a distribution of values in a 2x3 contingency table, given the number of observations in each cell. 
 Fisher's Exact Test Calculator for a 3X3 Contingency Table This calculator uses the FreemanHalton extension of Fisher's exact test to compute the (twotailed) probability of obtaining a distribution of values in a 3x3 contingency table, given the number of observations in each cell. 
 Interval Probability Calculator for the Uniform Distribution This calculator will compute the probability of a specified interval under a (continuous) uniform distribution, given the values of the upper and lower boundaries of the distribution and the values of the upper and lower boundaries of the probability interval. 
 Joint Probability Calculator This calculator will compute the probability of two events A and B occurring together (i.e., the joint probability of A and B), given the conditional probability of event A, and the probability of event B. 
 OneTailed Area Under the Standard Normal Distribution Calculator This calculator will tell you the onetailed (righttail) area under the standard normal curve, given a Zscore (i.e., the onetailed probability from the zscore to positive infinity). 
 pValue Calculator for a ChiSquare Test This calculator will tell you the onetailed (righttail) probability value for a chisquare test (i.e., the area under the chisquare distribution from the chisquare value to positive infinity), given the chisquare value and the degrees of freedom. 
 pValue Calculator for a Student tTest This calculator will tell you the onetailed and twotailed probability values of a ttest, given the tvalue and the degrees of freedom. 
 pValue Calculator for an FTest This calculator will tell you the probability value of an Ftest, given the Fvalue, numerator degrees of freedom, and denominator degrees of freedom. 
 pValue Calculator for Correlation Coefficients This calculator will tell you the significance (both onetailed and twotailed probability values) of a Pearson correlation coefficient, given the correlation value r, and the sample size. 
 Poisson Probability Calculator This calculator will compute a Poisson probability (i.e., the probability of a specific number of events occurring within a specific number of fixed intervals of time or space), given the total number of events observed, the expected number of events per interval, and the total number of intervals. 
 Significance of the Difference between Two Correlations Calculator This calculator will determine whether two correlation coefficients are significantly different from each other, given the two correlation coefficients and their associated sample sizes. Values returned from the calculator include the probability value and the zscore for the significance test. A probability value of less than 0.05 indicates that the two correlation coefficients are significantly different from each other. 
 Significance of the Difference between Two Slopes Calculator This calculator will determine whether the slopes of two lines are significantly different from each other, given the slope, standard error, and sample size for each line. Values returned from the calculator include the probability value, the tvalue for the significance test, and the degrees of freedom. A probability value of less than 0.05 indicates that the two slopes are significantly different from each other. 
 Sobel Test Calculator for the Significance of Mediation This calculator uses the Sobel test to tell you whether a mediator variable significantly carries the influence of an independent variable to a dependent variable; i.e., whether the indirect effect of the independent variable on the dependent variable through the mediator variable is significant. This calculator returns the Sobel test statistic, and both onetailed and twotailed probability values. 
 TwoTailed Area Under the Standard Normal Distribution Calculator This calculator will tell you the twotailed area under the standard normal curve, given a Zscore (i.e., the twotailed probability from +/ the Zscore to infinity on both tails of the distribution). 
 Union Probability Calculator This calculator will compute the probability of event A or event B occurring (i.e., the union probability for A and B), given the probability of event A, the probability of event B, and the joint probability of events A and B. 
 Probability Density Function (PDF) Calculator for the Beta Distribution This calculator will compute the probability density function (PDF) for the beta distribution, given values of the shape parameters and the point at which to evaluate the function. 
 Probability Density Function (PDF) Calculator for the ChiSquare Distribution This calculator will compute the probability density function (PDF) for the Chisquare distribution, given the point at which to evaluate the function x, and the degrees of freedom. 
 Probability Density Function (PDF) Calculator for the FDistribution This calculator will compute the probability density function (PDF) for the Fisher Fdistribution, given the numerator and denominator degrees of freedom, and the point at which to evaluate the function x. 
 Probability Density Function (PDF) Calculator for the Noncentral tDistribution This calculator will compute the probability density function (PDF) for the noncentral tdistribution, given a tvalue, the degrees of freedom, and the value of the noncentrality parameter. 
 Probability Density Function (PDF) Calculator for the Normal Distribution This calculator will compute the probability density function (PDF) for the normal distribution, given the mean, standard deviation, and the point at which to evaluate the function x. 
 Probability Density Function (PDF) Calculator for the Standard Normal Distribution This calculator will compute the probability density function (PDF) for the standard normal distribution, given the point at which to evaluate the function x. 
 Probability Density Function (PDF) Calculator for the tDistribution This calculator will compute the probability density function (PDF) for Student's tdistribution, given a tvalue and the degrees of freedom. 
 Probability Density Function (PDF) Calculator for the Uniform Distribution This calculator will compute the probability density function (PDF) for the (continuous) uniform distribution, given the values of the upper and lower boundaries of the distribution and the point at which to evaluate the function. 
 Apriori Sample Size Calculator for Multiple Regression This calculator will tell you the minimum required sample size for a multiple regression study, given the desired probability level, the number of predictors in the model, the anticipated effect size, and the desired statistical power level. 
 Adjusted Rsquare Calculator (Population Rsquare) This calculator will compute an adjusted Rsquare value (i.e., the population squared multiple correlation), given an observed (sample) Rsquare, the number of predictors in the model, and the total sample size. 
 Beta (Type II Error Rate) Calculator for Multiple Regression This calculator will tell you the beta level for your study (i.e., the Type II error rate), given the observed probability level, the number of predictors, the observed Rsquare, and the sample size. 
 Confidence Interval Calculator for a Predicted Value of a Regression Equation This calculator will compute the 99%, 95%, and 90% confidence intervals for a predicted value of a regression equation, given a predicted value of the dependent variable, the standard error of the estimate, the number of predictors in the model, and the total sample size. 
 Critical Fvalue Calculator This calculator will tell you the critical value of the Fdistribution, given the probability level, the numerator degrees of freedom, and the denominator degrees of freedom. 
 Effect Size Calculator for Multiple Regression This calculator will tell you the effect size for a multiple regression study (i.e., Cohen's fsquare), given a value of Rsquare. 
 fsquare Effect Size Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for the fsquare effect size associated with a multiple regression study, given the fsquare value, the number of predictors in the model, and the total sample size. 
 FValue and pValue Calculator for Multiple Regression This calculator will tell you the Fisher Fvalue for a multiple regression study and its associated probability level (pvalue), given the model Rsquare, the number of predictors in the model, and the total sample size. 
 Posthoc Statistical Power Calculator for Multiple Regression This calculator will tell you the observed power for your multiple regression study, given the observed probability level, the number of predictors, the observed Rsquare, and the sample size. 
 Rsquare Calculator (from an fsquare Effect Size) This calculator will compute an Rsquare value for a multiple regression model, given Cohen's fsquare effect size for the model. 
 Rsquare Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for an Rsquare value (i.e., a squared multiple correlation), given the value of the Rsquare, the number of predictors in the model, and the total sample size. 
 Regression Coefficient Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for a regression coefficient, given the value of the regression coefficient, the standard error of the regression coefficient, the number of predictors in the model, and the total sample size. 
 Regression Intercept Confidence Interval Calculator This calculator will compute the 99%, 95%, and 90% confidence intervals for a regression intercept (i.e., the regression constant), given the value of the regression intercept, the standard error of the regression intercept, the number of predictors in the model, and the total sample size. 
 Significance of the Difference between Two Slopes Calculator This calculator will determine whether the slopes of two lines are significantly different from each other, given the slope, standard error, and sample size for each line. Values returned from the calculator include the probability value, the tvalue for the significance test, and the degrees of freedom. A probability value of less than 0.05 indicates that the two slopes are significantly different from each other. 
 Apriori Sample Size Calculator for Hierarchical Multiple Regression This calculator will tell you the minimum sample size required for a hierarchical multiple regression analysis; i.e., the minimum sample size required for a significance test of the addition of a set of independent variables B to the model, over and above another set of independent variables A. The value returned by the calculator is the minimum sample size required to detect an effect of the specified size, probability level, and power level for the addition of set B to the model. 
 Apriori Sample Size Calculator for Multiple Regression This calculator will tell you the minimum required sample size for a multiple regression study, given the desired probability level, the number of predictors in the model, the anticipated effect size, and the desired statistical power level. 
 Apriori Sample Size Calculator for Structural Equation Models This calculator will compute the sample size required for a study that uses a structural equation model (SEM), given the number of observed and latent variables in the model, the anticipated effect size, and the desired probability and statistical power levels. The calculator will return both the minimum sample size required to detect the specified effect, and the minimum sample size required given the structural complexity of the model. 
 Apriori Sample Size Calculator for Student tTests This calculator will tell you the minimum required total sample size and pergroup sample size for a onetailed or twotailed ttest study, given the probability level, the anticipated effect size, and the desired statistical power level. 
 Apriori Sample Size Calculator for Student tTests This calculator will tell you the minimum required total sample size and pergroup sample size for a onetailed or twotailed ttest study, given the probability level, the anticipated effect size, and the desired statistical power level. 
 Beta (Type II Error Rate) Calculator for a Student tTest This calculator will tell you the beta level for a onetailed or twotailed ttest study (i.e., the Type II error rate), given the observed probability level, the observed effect size, and the total sample size. 
 Confidence Interval Calculator for the Population Mean This calculator will compute the 99%, 95%, and 90% confidence intervals for the mean of a normal population, given the sample mean, the sample size, and the sample standard deviation. 
 Cumulative Distribution Function (CDF) Calculator for the Noncentral tDistribution This calculator will compute the cumulative distribution function (CDF) for the noncentral tdistribution (i.e., the area under the noncentral tdistribution from negative infinity to t), given a tvalue, the degrees of freedom, and the value of the noncentrality parameter. 
 Cumulative Distribution Function (CDF) Calculator for the tDistribution This calculator will compute the cumulative distribution function (CDF) for Student's tdistribution (i.e., the area under the tdistribution from negative infinity to t), given a tvalue and the degrees of freedom. 
 Effect Size (Cohen's d) Calculator for a Student tTest This calculator will tell you the (twotailed) effect size for a Student ttest (i.e., Cohen's d), given the mean and standard deviation for two independent samples of equal size. 
 OneSample tTest Calculator This calculator will conduct a complete onesample ttest, given the sample mean, the sample size, the hypothesized mean, and the sample standard deviation. The results generated by the calculator include the tstatistic, the degrees of freedom, the critical tvalues for both onetailed (directional) and twotailed (nondirectional) hypotheses, and the onetailed and twotailed probability values associated with the test. 
 pValue Calculator for a Student tTest This calculator will tell you the onetailed and twotailed probability values of a ttest, given the tvalue and the degrees of freedom. 
 Posthoc Statistical Power Calculator for a Student tTest This calculator will tell you the observed power for a onetailed or twotailed ttest study, given the observed probability level, the observed effect size, and the total sample size. 
 Probability Density Function (PDF) Calculator for the Noncentral tDistribution This calculator will compute the probability density function (PDF) for the noncentral tdistribution, given a tvalue, the degrees of freedom, and the value of the noncentrality parameter. 
 Probability Density Function (PDF) Calculator for the tDistribution This calculator will compute the probability density function (PDF) for Student's tdistribution, given a tvalue and the degrees of freedom. 
 Student tValue Calculator This calculator will tell you the Student tvalue for a given probability and degrees of freedom. Student tvalues for both onetailed (righttail) and twotailed probabilities will be returned. 
 tStatistic and Degrees of Freedom Calculator This calculator will compute the tstatistic and degrees of freedom for a Student ttest, given the sample mean, the sample size, the hypothesized mean, and the sample standard deviation. 
 tValue Calculator for Correlation Coefficients This calculator will tell you the tvalue and degrees of freedom associated with a Pearson correlation coefficient, given the correlation value r, and the sample size. 


