Who this applies to
These terms govern your use of statpower.org (“StatPower”), a free study-planning tool operated by Data Analysis & Statistical Solutions (“DASS”). By using StatPower, you agree to these terms. If you don’t agree, please don’t use the site.
Your results are planning estimates
StatPower calculates sample size, statistical power, and minimum detectable effects for a small set of standard designs, using the methods described on the methodology page. Every result depends entirely on the inputs you choose, especially the expected effect size, and on whether your study actually matches the design you selected.
Results do not account for clustering, repeated measures, attrition, multiple outcomes, unequal allocation, or other features of many real studies unless the tool says so. You are responsible for checking that a result fits your design and assumptions before using it in a protocol, grant application, ethics submission, preregistration, or publication.
No professional advice
StatPower and its explanations are general information, not advice about your specific study. Using the tool does not create a consulting or client relationship with DASS. If you need a power analysis you can rely on for a real decision, that is what a design-specific engagement with DASS is for, and it is governed by its own written agreement.
Using StatPower
You are welcome to use StatPower for research, teaching, and professional planning, and to include its numbers and its reporting sentence in your own work. Citing StatPower is appreciated but not required.
Please don’t attempt to disrupt the site or gain unauthorized access to it, scrape it or send automated traffic at a volume that burdens it, or present StatPower’s output as a review or endorsement of your study by DASS.
Ownership
The StatPower name, logo, design, text, and code are owned by DASS and protected by copyright and other applicable laws. You may quote brief excerpts with attribution and a link. The results you generate are yours to use.
No warranty; limitation of liability
StatPower is provided “as is” and “as available,” without warranties of any kind, express or implied, including accuracy, completeness, availability, or fitness for a particular purpose. We may change, suspend, or discontinue any part of it at any time.
To the fullest extent permitted by law, DASS is not liable for any direct, indirect, incidental, or consequential damages arising from your use of StatPower or reliance on its results, including decisions about study design, funding, or publication.
Other terms
Privacy. How StatPower handles information is described in the Privacy Policy. In short: your calculator inputs stay in your browser.
Other websites. StatPower links to sites it doesn’t operate, including statisticalsolutions.org. Those sites have their own terms and policies.
Changes. We may update these terms as StatPower changes. The version on this page is always the current one, and continuing to use the site after an update means you accept the revised terms.
Governing law. These terms are governed by the laws of the Commonwealth of Massachusetts, without regard to its conflict-of-laws principles.
Contact
Questions about these terms? Email Dr. Nedim Yel at nedimyel@statisticalsolutions.org.