An educational psychologist investigated the effect of reading format on reading comprehension. Participants were tasked with reading a complex scientific article on astrobiology. Six participants read the article on a digital screen (with active backlighting). A different group of six participants read the article on printed paper.
Afterwards, all participants completed a comprehension test scored out of 40. The data collected, along with preliminary rankings, is presented in the table below.
| Comprehension score (max. 40) | |||||
|---|---|---|---|---|---|
| Digital screen group | Printed paper group | ||||
| Participant | Score | Rank | Participant | Score | Rank |
| a | 32 | 9.5 | a | 18 | 2 |
| b | 35 | 11 | b | 20 | 3 |
| c | 28 | 6 | c | 15 | 1 |
| d | 26 | 5 | d | 38 | 12 |
| e | 30 | 8 | e | 22 | 4 |
| f | 29 | 7 | f | 32 | 9.5 |
| n1=6n_1 = 6n1=6 | n2=6n_2 = 6n2=6 |
Outline two ways that using an independent measures design could affect the validity of this study.
