Purpose

Information is published for several purposes.

Public reports
Most organisations publish reports about specific aspects of their work that are aimed at a wide audience. These are often regular publications such as annual summaries about aspects of the state if the organisation, but specialist reports and press releases may be written about specific projects or topics. Brevity is important, so the information in reports must be presented concisely and clearly.
Executive reports
These are usually internal reports about specific topics. It can often be assumed that the readership is more technically sophisticated, so more advanced analyses and presentation can be used.
Archival and regular publications
There is often a need to provide access to detailed data to allow further analysis. Large tomes of tabulated data were once published by government organisations, but such data are often provided electronically now. In spreadsheet format, users can easily input the data into other programs
Some organisations have a statutary obligation to provide certain information at regular intervals (often annually). This information is usually archival, but sometimes a 'Yearbook' is published for a wider audience and its format is therefore closer to a report.

Care must be taken to present information clearly in all types of publication, but it is most important for publications aimed at the general public and least important for archival data.

Publication medium

A few decades ago, all information was published in black and white on paper. Colour is now used more often in paper publications, but an increasing proportion of publications are produced only electronically for display on a computer. Such computer publications are often provided over the internet.

The use of colour in both paper-based and electronic publications makes it much easier to present information clearly, especially in graphs.

Quality and resolution of medium
Colour print on glossy paper is best but expensive. Computer screens also show colour but their resolution is relatively low — typically a tenth of the number of 'dots' per unit area that would be used on paper. The poorer resolution of a computer limits the type size of text and the detailed information that can be presented, especially if the screen is small. Newsprint and many other low-quality colour printing processes have reasonable resolution but allow only limited if any use of colour.
Cost
It is much cheaper to make large quantities of information available on the internet than on paper. However the cost of producing publications on paper tends to ensure that they are designed better — there is a conscious effort to cut back the presentation to the essentials that convey the intended message. It is much harder to create a user interface that allows users to easily find information that is published on a web site. It is critically important that web sites are easy to navigate and the structure of the web site must be included in the cost of publishing the information.
Format
Many reports are published on the internet as 'pdf' files. These are the electronic equivalent of a series of printed pages and can be laid out with text and graphics in the same way as is done on paper. Although pdf files are still limited by the screen resolution of the computer, it is possible to zoom in and to print them at much higher resolution.
An alternative is to publish information directly as web pages that can be viewed from a web browser. Although the ability to format such web pages was limited until recently, web pages can now be laid out almost as flexibly as on paper (using functionality called cascading style sheets). It is possible to make a web site interactive, both for navigation around the site and for interacting with individual pages. (CAST itself is an example of what is possible.)
Archival data can be directly provided on the internet in spreadsheet format. Alternatively, large organisations often have a web-based interface that can extract information from a large behind-the-scenes database. For example, the United Nations provides a wealth of information that can be accessed at http://unstats.un.org/unsd/cdb.

Some types of publication must be printed on paper in order to reach a wide audience. In contrast, archival information is best provided on a web site because there are likely to be few users and they will find the information most useful electronically. However with computers and internet connections becoming more common, a well-designed web site is becoming a very powerful and flexible way to present information.

There is no perfect publication medium, but a well-designed web site should be considered.