Standardisation of CoPS

CoPS underwent a full national re-standardisation in May – July 2019. The standardisation was conducted in 43 schools (England n = 32; Northern Ireland n = 8; Wales n = 1; Scotland n = 1; Republic of Ireland n = 1). Of those schools where an Ofsted assessment has been published, 27% were rated as Outstanding, 64% were rated as Good and 9% were rated as Requiring Improvement (which compares reasonably well to national figures for the 2018/19 academic year: 20% Outstanding; 66% Good; 11% Requires improvement). The number of students on the roll for the sample schools ranged from 30 to 683, with an average of 262.

School characteristics (where these were available on or the equivalent websites for Scotland, Wales, Northern Ireland and the Republic of Ireland) for the sample schools were compared to the national average (for English state-funded Primary schools) – see Table 6. It can be seen that the schools overall included a slightly higher proportion of girls than the national average and a slightly lower proportion of pupils with an ECHP than the national average.


Table 6. Characteristics of schools within the standardisation sample

Within the selected schools, students were included in the standardisation on an entire class basis, to avoid any selection bias. The number of students completing each subtest, within each age group of the standardisation sample, are shown in Table 7.


Table 7. Students per age group for each subtest

Demographic information concerning the students within the standardisation sample are given in Table 8 (note that information was not provided for all students). Population parameters are also provided, but these are based only on English state-funded Primary schools, whereas the sample also includes students from Northern Ireland, Wales, Scotland and the Republic of Ireland, so the comparisons are limited. It can be seen that the sample included a slightly higher proportion of female students than the national average for English state-funded Primary schools. With regards to ethnicity, the sample has a higher proportion of Asian students than is found in the population and lower proportions of White and Black students, although ethnicity information was not provided for 12.6% of the sample (proportions of Mixed and Other ethnicity students within the sample is representative of population parameters). The number of students within the sample who are eligible for Free School Meals is similar to that within the population. With regard to language, the percentage of students within the sample speaking English as an Additional Language is slightly higher than the population average. The proportion of students within the sample with a diagnosed SEN is similar to that within the population, whereas those with an Education, Health and Care plan is a little lower than the national average. However, the CoPS sample only includes students aged 4–7, who are less likely to have an EHCP already in place than those within the full primary age range, which the population parameters are based on.


Table 8. Demographic details of sample

* Based on DfE school census data for English state-funded Primary schools, January 2019

Of the standardisation sample, 91% undertook the tests using desktop computers, whilst 9% used tablets. Analysis showed that on seven of the eight main tests (not including Clown), there was evidence of a platform effect, with students using desktops outperforming those using tablets. However, it is possible that these differences are due to school effects, with the schools that used tablets showing higher proportions of students being eligible for free school meals, and more students with SEND support/ECHPs than the schools using desktops.

The sample data has been weighted according to age, gender and SEND proportion against population parameters. Using a non-parametric age-standardisation model, the raw scores for each age group were transformed into Standardised Age Scores (SAS) with a mean of 100 and a standard deviation of 15. This builds on previous work conducted by Schagen (1990). SAS scores for the subtests range from 65 to 135, although on subtests where there is a ceiling effect, the SAS is capped at the upper end. However, the caps do not distort the scoring at the lower end of abilities, which are those most commonly interested in.

Table 9 shows the correlations between the main CoPS subtests (i.e. all except Clown). The correlations range from .194 to .491. All correlations are significant at the p<.001 level. The CoPS subtests all measure distinct constructs. However, the table indicates that those subtests where there is some overlap in the underlying skills (e.g. Rabbits, Crayons and Letters all being visual subtests) show higher levels of correlation than those subtests utilising entirely different skills (e.g. Rhymes and Letter names; or Wock and Letters).


Table 9. Intercorrelations between subtests

* all correlations are significant at p<.001; (N is shown in brackets)

In order to check for any gender bias, comparisons were made between males and females (where gender had been identified) on each subtest (see Table 10). A small effect was found on Crayons slightly favouring girls. There were no other gender effects.


Table 10. Gender differences

* Cohen’s d is a measure of effect size of the difference between two means

Checks were also made for ethnic group bias. Due to the small numbers in some ethnic minority groups, comparisons were made between White students and Other ethnic groups combined (where ethnicity had been identified) on each subtest (see Table 11). Small effects were found on Races and Rhymes, slightly favouring White students. There were no other ethnicity effects.


Table 11. Ethnic group differences

* Cohen’s d is a measure of effect size of the difference between two means