# Power Calculators

These calculators perform power and sample size calculations for a variety of hypothesis tests.

### Hypotheses on Means

Compare a mean, $$\mu$$, to a known value, $$\mu_0$$
Compare the means from two groups using a parallel study design.
Compare the means from two groups using a crossover study design.
Compare the means from several groups using One-Way ANOVA. This calculator can be used for simultaneous or pairwise comparisons.
Compare the means from multiple groups using a multi-sample William's study design.

### Hypotheses on Proportions

#### Using Large Sample Theory:

Compare a proportion, $$p$$, to a known value, $$p_0$$.
Compare proportions from two groups using a parallel study design.
Compare proportions from multiple groups using a crossover study design.
Compare an odds ratio to 1 using a parallel study design.
Compare an odds ratio to 1 using a crossover study design.
Compare a set of proportions using one-way ANOVA.
Compare the proportions from two groups using a multi-sample William's study design.

#### Using Exact Calculations:

Compare a proportion, $$p$$, to a known value, $$p_0$$.
Compare proportions from two groups using a parallel study design using Fisher's Exact Test.

### Hypotheses on Time To Event Data

Compare the ratio of two survival curves.
Compare the difference of two hazard ratios estimated using an exponential time to event model.

### Hypotheses on Variances

Compare the total variability of two groups measured in a 2 by 2 crossover study.
Compare the total variability of two groups measured in a 2 by 2M crossover study.
Compare the total variability of two groups measured in a parallel study with replication within subjects.
Compare the total variability of two groups measured in a parallel study without replication within subjects.
Compare the intersubject variability within a group measured in a crossover study.
Compare the intersubject variability within a group measured in a parallel study.
Compare intrasubject variability measured in a crossover study.
Compare intrasubject variability measured in a parallel study.
Compare the intrasubject coefficient of variation (CV) within a group measured in a parallel study. This calculator supports both simple random effects and conditional random effects models to estimate the intrasubject CV.

### Hypotheses on Non-Parametric Statistics

Test the location of a sample using Wilcoxan signed rank test.
Test differences in the location of two sample using Wilcoxan rank sum test.
Test the value of Kendall's Coefficient.

### Hypotheses on Bioequivalence

Test the average bioequivalence of drugs using a 2 x 2 crossover design.
Test the population bioequivalence of drugs using using a 2 x 2 crossover design.

### Compare Goodness of Fit

Test the existence of a carry-over effect in a 2 by 2 carryover design with a binary outcome. This calculator assumes the use of McNemar's test to test the hypothesis.
Test the independence of two categorical variables with multiple strata using the Cochran-Mantel-Haenszel Test.
Test the independence of two categorical variables using the Likelihood Ratio Test.
Test the existence of a categorical shift in a binary outcome evaluated using McNemar's Test.
Test a categorical variables goodness of fit compared to a reference distribution using Pearson's Goodness of Fit Test.
Test the independence of two categorical variables using the Pearson's Test of Independence.
Test the existance of a categorical shift in a binary outcome evaluated using the Stuart-Maxwell Test.

### Compare Distribution

Test the normality of a sample based on a given distribution.

If there is a hypothesis that you will use but is not listed, let us know. We are always expanding our list of tools!