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Introduction This is the home page of the StatsToDo website. The site is under minimal maintenance following the retirement of its original author. The current maintainer is Nick Brown (nicholasjlbrown at gmail). About StatsToDo This site is not intended, and is insufficient, as a reference or teaching site for statistics. Over the years, programs were added according to needs of ongoing projects of a clinical academic department, in response to questions and suggestions, and as interests dictated. Therefore there is no systematic organisation of the information available, and otherwise important algorithms that have not been needed or noticed by the author may be missing. Many old programs, superceded by better ones, have been deleted, but some outdated program may still be present. Many, but not all, of the programs have been used to produce results that were accepted by the major clinical journals. Users should therefore consider this site as a data analysis tool box that may contain algorithms that are useful to their current needs, but not as a teaching resource or reference authority. Users should exercise their own judgements, and seek advice from experts when in doubt. Disclaimer Neither the original author nor the current maintainer of this site claims any expertise in statistics. The resources of this site are free to all who wish to use them. However, a condition of use is that the user accepts his/her own responsibility for using or reproducing any information obtained from the site or communications with the author. Copyrights All contents of the pages from this site, including programs in php, Javascript, R and Python codes, have been created by the author or maintainer personally, although text books, journal articles, and the www were widely consulted and copied during development. As far as we are aware, all sources used are in the public domain, fully referenced, and the copyrights of others have not been infringed. No LLMs or "vibe coding" have been used. The author reserves the copyright of contents of this site, mainly to avoid possible disputes. Users are free to copy any contents of the site (explanations, tables, algorithms) for their own use, on condition that they accept responsibility for the results produced. References and Acknowledgement Numerous enquiries have been received on how to reference the algorithms from StatsToDo. The usual accepted one is to place the url in angle brackets. e.g. <www.StatsToDo.com/MakeTable.php >. As web pages tends to be edited, it would be better to reference the text book or journal article that describe the algorithm in the first place. All algorithms from StatsToDo have references listed on the same page, and the user can access and read the references, accepts that the algorithm from StatsToDo correctly reflect the original descriptions, before referencing the original work. Technical Issues Numerical precision Non integer numerical output from StatsToDo are by default in 4 decimal places of precision, unless the situation warrants otherwise. Experience indicates that this is more than sufficient in most circumstances. As percent (%) is usually presented to 1 decimal point, probability to 2 or at most 3 decimal point, t,z,F, and Chi Square have little meaning after the second decimal point. Users should be aware that 4 decimal points of precision is often redundant, and edit numerical results before publication. Many mathematical procedures are iterative approximations. Depending on the power of the processor, and the limits of approximation set during computation, the results may differ. In addition, as processors are continuously upgraded and becomes more powerful, results produced from the same program may change over time. Experience indicates that numerical outputs may differ as much as 0.1% to 0.3% from different sources, and similar differences may occasionally be seen between results of current computation and static tables produced previously. Users should understand the cause of these differences, and not be confused or alarmed. If in doubt, user should enquire via the contact page or consult his/her own statistical advisor. Default Example Data In nearly all programs from this site, default example data are provided, to show the user the format of data input, and to provide an example of the results that are produced. The default examples are all artificially generated to demonstrate the procedures involved, and must not be interpreted as anything reflecting reality. The research model in each example is also deliberately simplistic, so that it does not distract the user from focussing on the statistical and computational aspects The sizes of the example data are also very small, so that the user can visualize the data and results easily, but do not reflect the required sample size for meaningful interpretation of results. After testing and understanding the program with the default example data, the user can then replace them with his/her own data to produce the required results.