Information Brief 98-3

How Significant Are Changes In My School's Average ACT Composite Score Over Time?

High school counselors and principals often ask us how to interpret their schools' ACT test results. The question they ask most frequently is "Does my school's average ACT Composite score differ significantly from last year's?" To help answer this question, ACT has developed a chart that helps you compare changes in your school's average ACT Composite score to those of other schools.

Why Do Average ACT Composite Scores Change?

The ACT Assessment is a curriculum-based achievement test designed to assess critical reasoning and higher-order thinking skills in four content areas: English, mathematics, reading, and science reasoning. The tests measure the skills students have developed through their high school course work, as well as their readiness to take college-level courses.

A school's average ACT Composite score is affected by a variety of factors. Some can be influenced or controlled by schools: the percentage of students completing the college core high school curriculum, the quality of instruction, appropriate counseling, and courses offered. Others, such as student motivation, effective study habits, parental support and guidance, changes in the number of ACT-tested graduates across years, and changes in a school's student population, are less susceptible to school influence or control.

Examining Your Average Score Changes

The chart below summarizes the changes in school average ACT Composite scores between 1997 and 1998.The results are grouped by number of ACT-tested graduates. School averages tend to be more variable from year to year if the number of tested graduates is small, and more stable if that number is large. Therefore, the chart is broken down into five size categories based on the number of ACT-tested graduates. To be included in the chart, a schoolmust have had at least 30 ACT-tested graduates each year. The average Composite score change (1998 school average minus 1997 school average) was calculated for each school. Then the schools' average score changes were ordered from highest to lowest within each size category and percentile ranks were calculated.

To use this table, first calculate your school's average Composite score change (1998 average minus the 1997 average). Second, locate the appropriate column for the number of your school's 1998 ACT-tested graduates. For example, suppose your school's average Composite score difference is 0.6, and you had 73 tested graduates in 1998 and 65 in 1997. Locate the Number of ACT-tested Graduates range (62–88), read down the column to 0.6, then read across to the first column listing the percentile ranks of score changes.

For this example, the school's average Composite score change relative to the number of tested graduates corresponds to the 75th percentile. That is, this average score change is as high as at least 75 percent of all school average score changes in the same size category. If, for example, your school's score change is 0.5 for the same range of tested graduates, then this score change lies between the 50th and 75th percentiles. This change is as high as at least 50 percent of the schools in the same size category, but not as high as the top 25 percent of the schools in the same size category.

Every summer, ACT mails to high schools with at least 30 ACT-tested graduates a comprehensive High School Profile Report, with an executive summary showing the school's average ACT Composite scores for the previous five years.

Average ACT Composite Score Changes for Schools Between 1997 and 1998
Percentile rank of school
average score changes
Number of 1998 ACT-tested graduates
30 – 44 45 – 61 62 – 88 89 – 144 more than 144
95th 1.9 1.6 1.4 1.2 1.0
90th 1.5 1.2 1.1 1.0 0.8
75th 0.9 0.7 0.6 0.6 0.5
50th 0.2 0.1 0.1 0.1 0.1
25th –0.5 –0.5 –0.4 –0.3 –0.2
10th –1.2 –1.1 –0.8 –0.7 –0.5
5th –1.6 –1.5 –1.2 –1.0 –0.7
Average change in school average 0.17 0.12 0.11 0.13 0.13
Number of schools 941 1352 1398 1485 1481