TEDS Data Dictionary

Description of Test

In this test of language ability, twins were asked to make inferences about the possible causes of given situations. Twins were asked to select two correct responses from a list of four possibilities. There were 11 items in the test. The items, together with the responses and correct answers, are shown in detail in the table of test items at the bottom of this page.

Each item started with a statement, consisting of two sentences, describing a situation. The first sentence described the initial context, while the second sentence described a later outcome; the question that followed asked for possible reasons for the outcome. From the four possible answers that were offered, only two were plausible or likely in the given context. Each item was presented in the following way:

1. The initial statement (two sentences) and then the question were played from an audio recording.
2. The statement and question were presented in text on the screen.
3. The four possible answers (A,B,C,D), which were the response options, also appeared as text on the screen.
4. Each of the four answers in turn was played from an audio recording; while it was being played, the letter next to it (A/B/C/D) was highlighted on the screen.
5. The twin selected two answers by clicking on them, then clicked on "OK". If the twin attempted to select three answers, or if the twin attempted to click "OK" after selecting zero or one answer, then a warning appeared and the item remained on screen.

As usual, a tutorial (including a practice item) was played before the test starts. The tutorial was used to establish whether the computer's sound was turned on, in order to discourage twins from attempting the test without sound.

Each item had a time limit of 70 seconds in which a twin had to answer. There were no branching or discontinue rules: each twin was presented with all 11 items, in numerical order.

Test Rules

• Scoring
  For each question, selection of the two correct answers gains a score of 3; selection of only one correct answer gains a score of 1; selection of no correct answers gains a score of 0.
  The maximum total score for the test is 33.
• Ordering of items
  Items are presented in ascending order of item number. There are no branching or discontinue rules.
• Timeout rule
  Each item has a time limit of 70 seconds within which the twin must select two answers and click on "OK"; timing starts after the four answers have all been played (in audio). If 70 seconds pass without the twin clicking on "OK", then the selected answers (if any) are submitted as the twin's response. The twin may still receive a non-zero score at this point: if two answers were selected, they are scored in the usual way; if one answer was selected, it receives one mark if correct. However, if no answers were selected, then the item is forfeited (with zero score). When the timeout occurs, the item is removed from the screen, to be replaced with a "next item" link to allow the twin to continue the test.

Item Variables

The item variables relating to the Inferences 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 as follows. See the web data cleaning page for further details.

• For timed out items, the item response variable is recoded from missing to -1, and the item answer time is recoded from 70 to missing (item scores are 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 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. This is the same as the order in which items were presented to twins in the test.