Description: Use these calculators for studies with quantitative, qualitative or survival outcomes
Link: Statistical tools: calculators
Who is this resource for: Clinical investigators, statisticians
Who created this resource: This site is run by crab.org, a non-profit cancer research organization that collaborates with the well-known Fred Hutchinson Cancer Center in Seattle, WA. Together they run swogstat.org, which is the data coordinating center for the National Cancer Institute-funded SWOG cancer clinical trials network.
What does this resource offer: This website provides on-line tools to estimate the sample size needed for a study. Sample size calculations are supported for the following experimental designs, settings and outcome types:
- One-arm design for binary, numeric or survival outcome,
- Two-arm design for binary, numeric or survival outcome,
- Non-inferiority test for a binary or survival outcome,
- Two-stage design for a binary outcome,
- Testing for an interaction between two factors for a binary outcome, and
- Estimating the power for a test of association between a continuous marker and survival.
The information required as input from the user is clearly identified, as is the output that will be generated by the program. Sample size or power can be estimated for two-sided or one-sided hypothesis tests. Other functionalities supported on this website include programs to estimate the expected number of events for planned one-arm or two-arm survival studies, binomial confidence intervals, Chi-square tests for contingency tables, Kruskal-Wallis tests, probability of observing a rare event for a given sample size, and probabilities for binomial, normal, Poisson and chi-square distributions.
Helpful hints: Click on “Help document” to find the equation and assumptions used and a citation for each tool.