PIRLS 2021 International Results in Reading
Countries’ Reading Achievement
Average Reading Achievement and Scale Score Distributions
The overall achievement results for the 57 PIRLS 2021 participating countries and 8 benchmarking participants are presented in three exhibits.
- Exhibit 1.1 shows the average reading achievement and scale score distributions for the 43 countries and 5 benchmarking participants that collected their data at the end of the fourth grade.
- For the countries in Exhibit 1.1, Exhibit 1.2 provides significance tests for differences between country averages. Results flagged as significant have a 1 in 20 error level. There is a 5 percent chance of declaring the sample differences significant, even though the true difference is zero.
- Exhibit 1.3 includes the average reading achievement and scale score distribution for all 57 countries and 8 benchmarking entities, including the results for the students in the 14 countries and 3 benchmarking entities (half a year older) that delayed data collection until the beginning of the fifth grade (highlighted in pink).
For the 43 countries and 5 benchmarking entities that assessed fourth grade students at the end of the school year, Exhibit 1.1 includes each country’s average scale score with its 95 percent confidence interval as well as the range in performance for the middle half of the students (25th to 75th percentile—interquartile range) and the extremes (5th and 95th percentiles). The 43 countries are presented according to their average achievement in descending order. Please note that the countries annotated with a bowtie (⋈) assessed their fourth grade students at the end of the fourth grade school year, but one calendar year later than initially planned. The benchmarking participants are in a separate section at the bottom of the exhibit for ease of comparison.
The results indicate that these 43 countries had relatively high achievement in reading at the fourth grade as a group. The fourth grade students in almost three-fourths (30 out of the 43 countries) had higher achievement than the scale centerpoint of 500 (a point that is stable across assessment cycles, see “History of the PIRLS Reading Achievement Scale”). As in previous cycles, the results also reveal that although the differences from country to country in average achievement were often small (considerable overlapping of confidence intervals), there was a substantial range in performance of nearly 300 scale score points from the top-performing to the lower-performing countries.
History of the PIRLS Reading Achievement Scale
The PIRLS reading achievement scale was established in PIRLS 2001, based on the achievement across all participating countries, treating each country equally. Students’ achievement is placed on the scale with the successive PIRLS cycles, most recently for PIRLS 2021. Reporting the achievement data from each successive PIRLS assessment on the PIRLS scale enables monitoring increases or decreases in achievement across assessment cycles. The scale has a typical range of achievement between 300 and 700. A centerpoint of 500 was set to correspond to the mean of overall achievement in 2001, with 100 points set to correspond to the standard deviation. PIRLS uses the scale centerpoint as a point of reference that remains constant from assessment to assessment.
The achievement distributions in Exhibit 1.1 show a large within-country range in many of PIRLS 2021 countries—about 200 points or even larger between lower- and higher-performing students. When considering average achievement, it is important to keep in mind the sizable variations within countries, and that every country has some very good readers as well as some struggling readers.
For the countries shown in Exhibit 1.1, Exhibit 1.2 provides significance tests for differences in average estimated reading achievement between one country and another country. Exhibit 1.2 is based on a traditional approach of testing for significance of differences and does not provide information about practical significance. Significance in the statistical sense means that the size of the difference is surprising compared to the standard error of the difference. In the exhibit, a 5 percent error rate was used to calculate whether a difference was flagged as significant or not. Differences should be triangulated with other data in order to come to meaningful interpretations of what the differences imply in terms of improving reading education in the countries (see Chapter 13 in Methods and Procedures: PIRLS 2021 Technical Report).
In Exhibit 1.2, reading across a country row provides a way to compare that country’s average achievement to the average achievement of each of the other PIRLS 2021 countries shown across the top of the exhibit. Looking across the row for Singapore—the first country listed—shows an entire row of up arrows (▲), indicating that Singapore had higher average achievement (significant at p < α = 0.05) than each one of the other countries.
Hong Kong SAR and the Russian Federation had the next highest average reading achievement. Although these two countries had lower average achievement (▼) than Singapore, each had higher estimated average achievement than the rest of the other countries in the exhibit. Going down the exhibit, looking across each row in turn, England (with its assessment conducted in 2022 as noted by the bowtie, ⋈) had lower average achievement than Singapore, Hong Kong SAR, and the Russian Federation but higher achievement than the rest of the other countries. Next, Finland, Poland, Chinese Taipei, and Sweden had lower average reading achievement than the top four countries, but these four countries did not have different average achievement from each other and both Finland and Poland had higher estimated average reading achievement than each of the other countries.
Exhibit 1.3 presents average reading achievement and scale score distributions for all 57 countries and 8 benchmarking entities that participated in PIRLS 2021. Once again, the countries are presented in order of average achievement from highest to lowest. The countries with delayed testing and older students are highlighted in pink. Comparing back to Exhibits 1.1 and 1.2 that indicated Singapore through Sweden as the eight countries with relatively higher achievement than most of each of the other participating countries, it can be seen that these eight countries have been joined by five of the 14 countries with older students.
Despite not being able to identify the impact of the delayed assessment, it is clear that the students in these five countries are very capable readers. Could this perhaps be a sign of recovery from the impact of COVID-19 in these countries? Unfortunately, PIRLS has no way of isolating the effects that delaying the assessment of the fourth grade cohort over the summer until the beginning of fifth grade may have had on the reading achievement of these students, so direct comparisons with countries that assessed students at the end of fourth grade need to be made with great care.