TEDS Data Dictionary

Description of Test

The test consisted of a series of written statements, each of which was either true or false. For each statement, the twin had click on either "Yes" (true) or "No" (false). The twin was asked to complete as many items as possible within a 3 minute time limit. There were 98 items: the questions and responses are tabulated further down this page in the table of items. It was feasible (but very difficult) to respond to all 98 items within 3 minutes. Any given twin taking the test would typically complete fewer than 98 items, because of the time limit. There was no branching, and no score-based discontinue rule.

The tutorial at the start of this test gave each twin the chance to try a couple of practice items, which were neither timed nor scored. The timing of the test was explained in the tutorial, before the main test itself starts.

There was a time limit of 40 seconds for each item in the test. After 20 seconds, a reminder appeared on screen, asking the twin to click on an answer. When the 40 second limit was reached, the item timed out and the next item would appear on screen. The timed out item was given a score of zero (with a missing response in the raw data). Because the test moved on automatically to the next item after timing out, it was possible for a series of items to time out in sequence, so "serial timeouts" could occur in this test. Such cases are excluded from the data if the number of timeouts is judged to be too large.

Because of the way the items were presented, with a strict overall time limit, the test was programmed to run entirely in the twin's web browser and data were only sent back to the server once the test was finished. As a result, if the test was interrupted in any way once it had started then the test ended without any data being recorded, and the test could not be resumed or re-started. The test was then labelled as "abandoned", and no item data were recorded. The twin then resumed the web battery at the next activity. Any of the following may have caused the test to be abandoned, once started: the twin's computer crashed; server software crashes; loss of internet connection; browser closed during test; twin clicked the browser's Back or Refresh buttons.

Test Rules

• Test timing rule
  Each twin is given a time limit of 3 minutes within which to answer as many items as possible. The test ends either when the twin has answered all 98 items, or when the 3 minutes have elapsed, whichever occurs sooner.
• Item timeout rule
  A timeout of 40 seconds applies to each item. After 40 seconds with no response, the item is forfeited with zero score, and the next item appears automatically on screen.
• Scoring
  For each question, there are two possible responses: yes (true) or no (false). The correct response is given a score of 1, and the incorrect response is given a score of 0. The maximum total score for the test is 98.
• Ordering of items
  Items are presented in ascending order of item number. There are no branching rules.

Item Variables

The item variables relating to the Reading Fluency test, as listed in the table below, were generated automatically by programs on the web server during the course of the test. Note that the dataset only includes data for completed tests. If a twin started the test but left it unfinished, then the data for the test were not used. Note also that the variable holding the total test score was also generated automatically on the web server, so this is treated as an item variable, not a derived variable.

In most cases the values of these variables have been left unaltered, although some have been recoded during data cleaning:

• For timed out items, the item response variable is recoded from missing to -1, and the item answer time is recoded from 40 to missing (item scores are 0)
• For items skipped due to the discontinue rule (the test time limit of 3 minutes), the item response variable is recoded from missing to -2, and the item score is recoded from missing to 0.
• For items that crashed or malfunctioned in any way, the item response variable is recoded from missing to -4, and the item score is recoded from missing to 0.
• For instances of abandoned or otherwise compromised tests, the status flag is recoded from 2 to 3, the data flag is recoded from 1 to 0, and all item variables are recoded to missing (test data deleted)
• For twins identified as random responders in this test, the status flag is recoded from 2 to 4, the data flag is recoded from 1 to 0, and all item variables are recoded to missing (test data deleted)

The test start and end dates and times, and item answer times, have not been retained in the dataset.

Test Items

The numbering of the items, shown in the table below, equates to the numbering used in the item variables. This is the same as the order in which items were presented to twins in the test.