In short
- StatPower uses privacy-conscious, cookie-free analytics (Vercel Web Analytics and Cloudflare Web Analytics) for aggregate page-visit statistics.
- There are no accounts, and nothing on this site asks for your name or email.
- Everything you type into the calculator stays in your browser.
- We do not use advertising trackers or build profiles of individual visitors.
- Three outside services see basic technical information when you load the site: our hosting and analytics provider, Vercel; Cloudflare, for analytics; and Google Fonts. All three are described below.
The calculator
Every calculation, including sample sizes, power, effect sizes, and the power curve, runs in JavaScript on your own device. Your inputs are not uploaded or logged, and StatPower does not save them between visits.
The “Copy reporting sentence” button writes text to your device’s clipboard. The reporting sentence and calculator inputs are not sent to Vercel Analytics, Cloudflare, or anywhere else.
What happens when you visit
Hosting and analytics. StatPower is hosted by Vercel and uses Vercel Web Analytics. The analytics service records aggregate page-visit information such as the page requested, referrer, approximate country, device type, browser, and operating system. It does not use cookies or collect calculator inputs. Vercel creates an anonymous visitor identifier from limited request information and a daily salt, then discards that identifier within 24 hours. We use the resulting statistics to understand which pages are useful and how visitors find the site, not to identify or profile people.
Cloudflare Web Analytics. StatPower also uses Cloudflare Web Analytics for aggregate traffic statistics, such as which pages are visited and where visitors come from. It does not use cookies, does not collect calculator inputs, and does not build a profile of you.
Fonts. StatPower’s typefaces are loaded from Google Fonts, so your browser requests them from Google’s servers. That request shares your IP address and browser information with Google, as described in the Google Fonts privacy FAQ and Google’s privacy policy. Google Fonts does not set cookies.
Links to other sites
Links such as “Review my design” lead to statisticalsolutions.org, the website of Data Analysis & Statistical Solutions (DASS), which created StatPower. Those consultation links include campaign labels identifying StatPower as the referral source; the labels contain no calculator inputs or personal information. Anything you share there, such as a contact form or a booking, is covered by the DASS privacy policy. Other external sites have their own policies.
Children
StatPower is a research-planning tool for adults and is not directed to children under 13. It does not knowingly collect information from anyone.
Changes to this policy
If StatPower changes its analytics or adds another feature that handles personal information, this page will be updated before that feature goes live, and the date at the top will change.
Contact
Questions about this policy? Email Dr. Nedim Yel at nedimyel@statisticalsolutions.org.