Comparing the Percentage of Students at Benchmark in a School in One Year to the Percentage Four Years Later

Oak Elementary began using Reading Mastery in grades K-3 in the fall of 2012. Teachers felt that their students were doing better after exposure to the program, but wanted to find out if changes in state assessment scores were educationally significant. In Spring 2016, four years after beginning the new curriculum, 65 percent of Oak Elementary third graders scored at the proficient or advanced level on the state assessment. In Spring 2012, before starting the new curriculum, 40 percent of Oak Elementary third graders scored at that level. Eighty-five students were tested in 2016 and 70 students were tested in 2012.

The information Oak Elementary teachers entered into the EIC and the results they obtained are shown below. Note that for this query the EIC specifies the lines in which data for each year should be entered. The data for the more recent year are entered first, followed by the data for the comparison year. The results clearly support the teachers’ impression of higher achievement. The effect size of .52 is far beyond the level considered educationally significant (and, in fact, just slightly less than the average effect size associated with the use of Reading Mastery that is reported in the research literature). The probability of .001 indicates that increases of this magnitude would occur by chance only once out of 1,000 times. The Improvement Index is also impressive, indicating that the average third grader at Oak Elementary in 2016 scored almost 20 percentile ranks higher than the average third grader in 2012.