Statistics calculators that show their working

Which tool do you need?

The twelve tools above fall into two groups that get used quite differently.

The statistics tools are for coursework, research and anyone who needs to turn numbers into a defensible result. If you have a value and need to know where it sits, start with the Z-score converter. If you have raw data and need to compare groups, go to the hypothesis tests. If you are not sure which test applies, the test wizard asks one question and points you at the answer.

The admission tools convert exam results into the scales five education systems actually use — Hong Kong's DSE and JUPAS points, Taiwan's GSAT levels, Japan's hensachi, Korea's CSAT standard score, and an explanation of why the Gaokao has no cross-province conversion at all.

The same mathematics underneath

These two groups look unrelated and are not. Japanese hensachi is a T-score. Korea's 표준점수 is the same T-score construction with different constants. Both are rescalings of the Z-score, which is the quantity the normal distribution page is built around.

If you understand that one conversion — how far a value sits from the mean, measured in standard deviations, and what share of the distribution that beats — you understand the machinery behind most of this site. The admission pages are that conversion applied to a specific exam, plus the local rules that surround it.

What this site does differently

• Every tool states its method. The two-sample t-test says it uses Student's rather than Welch's. The 2×2 chi-square says it applies no Yates' correction. The power analysis says it uses the normal approximation rather than the exact non-central distributions, and roughly how far that puts it from G*Power. You should not have to guess what a calculator did to your numbers.
• Reference data is labelled by confidence. University placement bands are marked as rough syntheses of public sources. The handful of per-programme admission figures are individually verified against the institution's own published statistics and each carries a link to its source. Where two sources disagreed, the entry was dropped rather than averaged.
• Nothing is uploaded. Every calculation runs in your browser. The one exception is the clearly-labelled optional AI analysis on the admission pages, which only sends anything when you press the button, and which the privacy policy describes in full.
• Limitations are stated where you will see them. Not in a footnote — on the page, next to the result, in the cases where they would change your conclusion.

What it is not

This is a free educational reference, not an authority. It is not affiliated with JUPAS, the HKEAA, the Taiwanese CEEC, KICE, Japan's National Center for University Entrance Examinations, China's Ministry of Education, or any university. The placement bands are orientation, not prediction, and no figure here should be used to make a decision without checking it against the official source — which each admission page links to directly.

For the full set of formulas, approximations and their known limits, see the methodology page. For who maintains this and how corrections are handled, see about.