Table 4
Average probabilities of successful performance, prose scale
 Selected proficiency scores
Prose level 150 200 250 300 350
1 48 81 95 99 100
2 14 40 76 94 99
3 6 18 46 78 93
4 2 7 21 50 80
5 * 2 6 18 40 68

* Probabilities are based on one task.


Table 5
Average probabilities of successful performance, document scale
 Selected proficiency scores
Document level 150 200 250 300 350
1 40 72 94 99 100
2 20 51 82 95 99
3 7 21 50 80 94
4 * 4 13 34 64 85
5 * <1 1 3 13 41

* Probabilities are based on one task.


Table 6
Average probabilities of successful performance, quantitative scale
 Selected proficiency scores
Quantitative level 150 200 250 300 350
1* 34 67 89 97 99
2 20 45 75 92 98
3 7 20 48 78 93
4 1 6 22 58 87
5 <1 2 7 20 53

* Probabilities are based on one task.


Similar kinds of interpretations can be made using the information presented for the document and quantitative scales. For example, someone who is at 250 on the document scale has, on average, an 82% chance of responding correctly to Level 2 tasks. His or her likelihood of responding correctly decreases to 50% for Level 3 tasks, 34% for Level 4 tasks, and only 3% for Level 5 tasks. Similarly, someone at 300 on the quantitative scale has a 78% chance of responding correctly to tasks at this level, but only a 58% chance with Level 4 tasks and a 20% chance with Level 5 tasks. Conversely, they would be expected to perform Level 1 and 2 tasks correctly more than 90% of the time.