WebPower WIKI

tools:index

johnny zhang (johnny@undisclosed.example.com) — 2026-05-29T09:01:24-0400

Tools * Univariate and multivariate skewness and kurtosis (Old version) * Normality evaluation of real data (New version)

start - [Acknowledgement]

johnny zhang (johnny@undisclosed.example.com) — 2026-01-17T17:36:13-0400

Statistical Power Analysis Online 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

service

johnny zhang (johnny@undisclosed.example.com) — 2025-12-12T20:38:00-0400

Statistical Consulting Service The WebPower development team provides consulting services, including statistical software support and assistance with experimental design and analysis to the research community. We provides assistance with experimental design and data analysis for all phases of research projects, including but not limited to:

effectsize:hedge_s_g - [Hedges' g for independent two-sample design]

johnny zhang (johnny@undisclosed.example.com) — 2025-04-27T14:21:07-0400

Hedges' g for independent two-sample design ---------- In independent two-sample design, the most popular effect size measure is defined as $$ \delta = \frac{\mu_1 - \mu_2}{\sigma} $$ where $\mu_1$ and $\mu_2$ are the population means of the two population and $\sigma$ is the population standard deviation which is assumed to be the same for the two populations.$$ g = d\times \frac{\Gamma(m/2)}{\sqrt{(m/2)} \Gamma[(m-1)/2]} $$$m = n_1 + n_2 - 2$$g$$$ var(g) = \frac{m(1+\tilde{n} \delta^2)}…

effectsize:cohen_s_d

johnny zhang (johnny@undisclosed.example.com) — 2025-04-27T14:02:08-0400

Cohen's d for independent two-sample design Calculator ---------- For studying the standardized group mean difference in an independent two-sample design, the most popular effect size measure is defined as $$ \delta = \frac{\mu_1 - \mu_2}{\sigma} $$ where $\mu_1$ and $\mu_2$ are the population means of the two groups and $\sigma$$$ d = \frac{\bar{y}_1 - \bar{y}_2}{\sqrt{\frac{(n_{1}-1)s_{1}^{2}+(n_{2}-1)s_{2}^{2}}{n_{1}+n_{2}-2}}} $$$n_1$$n_2$$\bar{y}_1$$\bar{y}_1$$s_1^2$$s_2^2$$\lambda…

effectsize:two-sample-t-test - [Calculator]

johnny zhang (johnny@undisclosed.example.com) — 2025-04-27T13:34:15-0400

Effect size and confidence interval for independent two-sample t-test ---------- Calculator ---------- How to use To use the calculator, information is needed according to whether you are using the raw data or summary statistics. When summary statistics are available $$ d = \frac{\bar{y}_1 - \bar{y}_2}{\sqrt{\frac{(n_{1}-1)s_{1}^{2}+(n_{2}-1)s_{2}^{2}}{n_{1}+n_{2}-2}}} $$$n_1$$n_2$$\bar{y}_1$$\bar{y}_1$$s_1^2$$s_2^2$$$ g = d\times \frac{\Gamma(m/2)}{\sqrt{(m/2)} \Gamma[(m-1)/2]} $$$m = n…

manual:tools:nonormal3.png - created

johnny zhang (johnny@undisclosed.example.com) — 2025-04-04T21:22:28-0400

manual:tools:nonormal2.png - created

johnny zhang (johnny@undisclosed.example.com) — 2025-04-04T21:22:28-0400

manual:tools:nonormal1.png - created

johnny zhang (johnny@undisclosed.example.com) — 2025-04-04T21:22:28-0400

effectsize:test.csv - created

johnny zhang (johnny@undisclosed.example.com) — 2024-01-06T21:35:25-0400

manual:m58fig.png - created

Ziqian Xu (ziqian@undisclosed.example.com) — 2023-04-12T14:57:46-0400

manual:simplemed.png - created

johnny zhang (johnny@undisclosed.example.com) — 2022-09-26T08:00:41-0400

avata.png - created

johnny zhang (johnny@undisclosed.example.com) — 2022-01-05T21:34:58-0400

manual:modmed15.png - created

Anqi (anqi@undisclosed.example.com) — 2021-12-20T09:22:31-0400

manual:modmed14.png - created

Anqi (anqi@undisclosed.example.com) — 2021-12-20T08:45:13-0400

manual:modmed7.png - created

Anqi (anqi@undisclosed.example.com) — 2021-12-13T01:19:14-0400

manual:modmed8.png

johnny zhang (johnny@undisclosed.example.com) — 2021-12-07T11:52:12-0400

logo.png

johnny zhang (johnny@undisclosed.example.com) — 2019-05-25T09:11:44-0400

logo-long-isdsa.png - created

johnny zhang (johnny@undisclosed.example.com) — 2019-05-23T08:17:07-0400

1_university_mark.jpg - created

johnny zhang (johnny@undisclosed.example.com) — 2019-05-23T07:54:33-0400