TEDS Data Dictionary

Description of Test

This test was identical to the version of the Vocabulary test that was previously used in the 10 Year study. The items themselves, and the test rules, were unchanged.

The test consisted of a series of vocabulary questions. For each question, there were either three or four possible responses; the twin selected a response by clicking on it on the screen. There were 30 items: the questions and responses are tabulated below. Any twin taking the test may have been presented with fewer than 30 items, because of the branching and discontinue rules, which are described below.

Each item was presented in two ways: as text on the screen, and as an audio recording. The text and audio file for each item were downloaded immediately before the item was presented. The audio recording was included as an aid to any twins with reading difficulties; this test was not intended to assess reading ability in addition to vocabulary knowledge.

This test was unaffected by item timeouts.

Test Rules

• Scoring
  For questions 1-8, the correct response is given a score of 2, and any of the two or three incorrect responses is given a score of 0.
  For questions 9-30, there are two correct responses; the best response is given a score of 2, and the second-best response is given a score of 1. Each of the other two (incorrect) responses is given a score of 0.
  The maximum total score for the test is 60.
• Branching rules
  
  • Start at item 5, and proceed to item 6.
  • If both items 5 and 6 are correct (scoring 2 each), give credit for items 1-4 (as though they had been answered correctly, gaining a score of 2 for each item), then proceed upwards from item 7.
  • If either item 5 or item 6 is incorrect (scoring 0), attempt the lower items (1-4) in reverse order. Then:
    • If any two successive items are correct (e.g. 4 and 3), then give credit for any of items 1-4 not yet attempted; then proceed upwards from item 7. Note that if either item 5 or item 6 is correct, and this is followed by a correct answer for item 4, then this results in an upward branch to item 7 (items 5 and 4 are treated as successive items, as are items 6 and 4, for this rule).
    • If no two successive items are correct, the test ends after item 1 has been attempted.
• Discontinue rule
  Discontinue the test after three scores of zero in any five consecutive items. This rule only applies from item 7 upwards. It does not include the branching items (5 and 6), nor does it include the lower items (1-4) if attempted.

Item Variables

The item variables relating to the Vocabulary 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 that the variable holding the total test score was also generated automatically on the web server. It is therefore treated as an item variable (it did not have to be derived as at age 10).

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

• For items skipped due to the discontinue rule, the item response variable is recoded from missing to -2, and the item score is recoded from missing to 0.
• For items skipped and credited due to upward branching, the item response variable is recoded from missing to -3 (the item score is already recorded as 1 on the web server).
• 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 crashed 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 and download 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. Note that this is not the same as the order in which items were presented to twins in the test (see branching rules above).