On the Correlation Summary page in the back of the Reading Fluency Progress Monitor books, what do the numbers in the Difficulty column mean?
The technical information in the back of the RFPM books summarizes the results of the field tests Read Naturally conducted with the fluency assessment passages. The numbers in the Difficulty column of the Correlation Summary table show the deviation between the results for a particular passage and the benchmark results.
For example, if the difficulty for a passage is listed as 3.1, it means that the field tests showed that this passage is slightly easier than the benchmark passages in RFBA for that grade. Specifically, students averaged 3.1 words correct per minute higher on the passage compared to the benchmark passages.
Similarly, if the difficulty for a passage is listed as -4.6, it means that field testing showed that this passage is slightly harder for students than the benchmark passages. Students averaged 4.6 words correct per minute less on the passage compared to the benchmark passages.
In all cases, the correlation between the RFPM passages and the benchmark passages was .90 or higher. High correlations (.8 or higher) between the monitoring passage and the benchmark passage means that the two passages are measuring the same skill (reading fluency) with a high degree of consistency.