Section 4.2: Creating Accessible Data Tables, Part 2
How to write a table summary
The "purpose of the summary attribute is to give a blind user the kind of table structure overview that a sighted user gains by scanning the table." [ 5, p.170 
]
This means that you do not give actual content that would be available from reading the table. The HTML Techniques for Web Content Accessibility Guidelines 1.0 [ 1 ] offers the following tips:
A summary of the relationships among cells is especially important for tables with nested headers, cells that span multiple columns or rows, or other relationships that may not be obvious from analyzing the structure of the table but that may be apparent in a visual rendering of the table. A summary may also describe how the table fits into the context of the current document. If no caption is provided, it is even more critical to provide a summary.
Activity 3: Writing a Table Summary
Try writing summaries for the following tables. Think about what information someone might need to understand the table if they were unable to see it. Possible summaries are provided but there is more than one correct answer based on the purpose of the table.
Question 1
Examine the table below, entitled "Results of psychology experiment".
| Participant | Administration Order | Test A Score | Test B Score |
|---|---|---|---|
| 1 | A-B | 50 | 100 |
| 2 | A-B | 55 | 95 |
| 3 | B-A | 60 | 96 |
| 4 | B-A | 62 | 98 |
Answer: "This table presents the results of Test A and Test B based on the order in which the test was administered. The pattern of results indicates that no matter in what order the tests were administered, Test B scores are significantly higher."
This summary tries to give an overview of the data that may be easy to see glancing at the table. Another way to provide this kind of summary/interpretative information is as textual content on the page. If an interpretation of the table is likely to be helpful for all users it should be part of the content of the page.
Question 2
What summary would you write for the Time Scale of Earth table ?
Answer: "This table provides the breakdown for each of the Eons, Eras, Periods, etc. in the development of the earth. It is a complex table with some cells associated with multiple cells to the right of them. For example, the 2 Eons encompass all 5 Eras listed. Moving top to bottom in the table presents most recent to oldest times."
This is a very complicated table. The purpose of the summary would be to help orient the user to the layout issues of the table. In all likelihood, screen reader users would either need a longer description to explain the data, or they need content on the page that explains the information presented in the table.
Question 3
What summary would you write for the Texas Politics table "Expenditures of the State of Texas" ?
Answer: "This table reports Texas state expenditures by major function of government. Employee benefits, education, and public safety and corrections have suffered decreases while other categories saw growth, notably natural resources/recreational services which grew by more than thirty-eight percent"
