WebPower is a collection of tools for conducting statistical power analysis online. WebPower can be used by anyone for free. To use the software now, click here. For a short tutorial on how to use WebPower, click here. For the online manual book (more than 30MB), please click here. To order a hard copy of the book, click the book cover below:

To cite WebPower, please use:

Zhang, Z., & Yuan, K.-H. (2018). Practical Statistical Power Analysis Using Webpower and R (Eds). Granger, IN: ISDSA Press.

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To see the more current usage statistics of WebPower, click here.

The development of WebPower is supported by a grant from the Department of Education (R305D140037). However, the contents of WebPower do not necessarily represent the policy of the Department of Education, and you should not assume endorsement by the Federal Government.

The operation of the project is also supported by

• Department of Psychology at Notre Dame
• Institute for Scholarship in the Liberal Arts at Notre Dame

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS OR ANYONE BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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We moved WebPower to a new and more powerful server. Everything should now work as expected. But if you encounter any problem, please let us know. Thanks. May 20, 2019