FAQ

Is StatsDirect free?

Yes. StatsDirect is free of charge for research, teaching and any other use, and there are no licence keys, trial periods or registrations: download it and install it. StatsDirect's own source code is open source under the MIT licence on GitHub; the installed program also contains components from other suppliers, such as the spreadsheet engine, which are supplied under their owners' licences and may not be redistributed on their own. The licence topic in the help gives the terms.

I have a licence key from an earlier version. Do I still need it?

No. Versions from 2024 onwards do not ask for a key. Install the current version over your old one.

Which computers run StatsDirect?

Windows: 64-bit Windows 10 (version 1809) or later, including Windows 11. The setup program installs Microsoft .NET 10 and the WebView2 runtime when they are missing.

Mac: Apple Silicon Macs running macOS 14 or later, as a zipped application from the Download page.

Intel Macs: run the Windows version in Windows under Parallels Desktop or VMware Fusion.

How do I install StatsDirect on many computers?

Use the MSI installer with your deployment tool; msiexec /i StatsDirect-x64.msi /qn installs it silently. The MSI expects the .NET 10 Desktop Runtime and the WebView2 Runtime to be present; the EXE setup installs them when they are missing. There are no licence keys to deploy.

How do I update?

StatsDirect checks for a newer version when it starts and offers to install it. You can also choose Help then Check for updates, or download the current version from the Download page and install it over your copy. On a Mac this works from version 1.1.2; with 1.1.1 or earlier, download the current zip once and replace StatsDirect in Applications. The Revisions page lists what each release changed.

My browser or Windows warns about the download. Is it safe?

A new release has not yet been downloaded often enough for Microsoft Edge and Windows to recognise it, so they may warn. In Edge, open the download's menu and choose Keep, then Show more and Keep anyway. If Windows then says "Windows protected your PC", choose More info and then Run anyway. Both installers carry a code signature; check that Windows names the publisher before you continue.

How do I cite StatsDirect in a paper?

Buchan I. StatsDirect statistical software, version (the version you used). https://www.statsdirect.com. England: University of Liverpool (the year).

Cite the statistical methods themselves from the references in the help, which lists the source of each method.

A doctoral thesis describing the scientific foundations of StatsDirect is at https://www.statsdirect.com/thesis/md.pdf.

Why do P values sometimes differ slightly from other packages?

StatsDirect uses exact (permutation) or simulated exact methods where many packages use large-sample approximations, for example in the Wilcoxon signed ranks test when there are ties. The help for each method says which calculation is used; see also exact tests on counts and P values.

Why are confidence intervals for proportions different from textbook formulae?

The simple textbook formulae perform poorly with small numbers. StatsDirect uses methods with good coverage, following Robert Newcombe's comparisons of methods for a single proportion and for the difference between proportions (Statistics in Medicine 1998;17:857-872, 873-890 and 2635-2650). See also confidence intervals.

Why does the exact interval for 0 events out of 30 look like a 97.5% interval?

The exact (Clopper-Pearson) interval limits the non-coverage in each tail to 2.5%. When every observation is the same, only one tail applies, so the upper limit (0.1157 for 0 of 30) is the one-sided 2.5% bound. This keeps the interval's meaning the same as the count falls to zero. Mid-P intervals are also offered.

Should I use multiple comparison tests after an analysis of variance?

Plan the comparisons in the design where you can, so that you are not dredging the data afterwards. Where a general method is needed, Tukey-Kramer serves well, and Dunnett's method when several groups are compared with a control; after a Kruskal-Wallis test, StatsDirect offers all-pairs contrasts. Ask a statistician if you are in doubt. See multiple comparisons and Kruskal-Wallis.

What is the difference between a missing value and zero?

An empty cell, or an asterisk, is a missing value and is left out of the analysis. Zero must be entered as 0 to count as an observation of zero. In counts, such as a contingency table, zero is a real observation, not a gap. See handling missing data.

Will I get rounding errors like those in Excel?

All arithmetic is IEEE double precision, about 16 significant digits, as in R and Excel. Tiny differences such as 1E-15 arise from how computers store decimal fractions in binary, not from the statistical method. StatsDirect's algorithms are written to limit the growth of rounding error, for example by leaving division as late as possible. See precision.

Can I use R with StatsDirect?

Yes. Every analysis offers an R script of its data and settings, which runs in the built-in R script window or console, or can be taken to R or RStudio. Any 64-bit R from version 4.2 is used, the newest installed; Set up R installs the current R when none is present.

What does the AI tutor send, and where?

The tutor and the script AI use your own ChatGPT account. Your questions go to OpenAI; your open documents are shared only when you have confirmed it, and that confirmation lasts for the application session, is asked for again when the set of open documents changes, and can be withdrawn at any time. Apart from the version check when the program starts and the downloads you ask for, such as R, nothing else leaves your computer: StatsDirect has no user accounts and sends no usage information. See the privacy policy.

How do I put a chart in Word, or edit it?

Charts are SVG vector graphics. Copy a chart from the report and paste it into Word as a picture, or save it as SVG or PNG. Reports are editable HTML and export to Word or PDF. Reports saved by earlier versions in RTF format still open, with their charts converted; MHTML and Word reports from earlier versions should be opened in Word and saved as HTML first. See the report window.

Is there a book about statistics with StatsDirect?

Statistical Testing in Practice with StatsDirect, by Cole Davis, introduces statistical testing in plain English, from simple comparisons to multiple regression, factor analysis and survival analysis. It describes an earlier version, so some menus differ. It was written and published independently; StatsDirect bears no responsibility for its content.

How do I report a problem or suggest an improvement?

Follow the three steps on the Support page: update to the current version, look in the help, then report the problem on GitHub or by email with the version, your system and what happened.