Biostats Calculator provides a comprehensive collection of biostatistical calculations. It is designed to provide easy access to the most common tests without resorting to a complex desktop statistics package. It also includes a sample size calculator for epidemiological studies, and can measure the utility and power of diagnostic tests.

Every test comes with a description, explaining when the test is applicable, an explanation on how to enter any required data, and a guide to interpreting the results. Interactive balloon help is also available, giving descriptions of technical terms.

= Available tests and calculations =

All tests generate p values indicating the significance levels of their results, as well as the listed statistics.

* Odds ratio
- confidence intervals

* Relative risk
- confidence intervals
- number needed to treat

* Chi-squared and Fisher exact tests
- enter any number of groups
- automatic test selection based on sample size
- chi-squared statistic

* Unpaired t-test
- enter data individually or as summary statistics
- confidence intervals for difference in means
- t statistic

* Mann-Whitney U test
- U statistic

* One-way ANOVA test
- F statistic

* Paired t-test
- confidence intervals for mean difference
- t statistic

* Wilcoxon signed-rank test
- W+ and W- statistics

* Pearson correlation
- correlation coefficient
- determination coefficient

* Spearman rank correlation
- correlation coefficient

* Sample size calculator
- enter Type I and Type II error rates (alpha and beta)
- allows unequal group sizes to be specified
- study can measure dichotomous variables (difference in proportions) or continuous variables (difference in means)
- required size of each group, and total size

* Diagnostic test utility
- specificity
- sensitivity
- false positive rate, false negative rate
- positive and negative predictive value
- positive and negative likelihood ratios

Future updates to the application will be free to all users.