KS3/4 - How is SPI (Subject Progress Index) calculated?

This article provides an in depth look at the Sisra exclusive measure, SPI (Subject Progress Index), and how it is calculated. This can help with troubleshooting figures, or for those who are interested in the detail behind the figures calculations.

What is SPI?

Subject Progress Index (SPI) is a sisra-exclusive measure which shows how a student has performed in a subject compared with all students with the same KS2 Prior in the Sisra Data Collaboration event published by your administrator. This can be useful to compare performance of students, qualifications, classes, faculties, filters, and more! Think subject Progress 8, but better!

You can check which Data Collaboration event the report has been published with from the ‘Data Collab’ bar within your report:

For example, the above would mean SPI is comparing students' performance to the exam performance of the 2023 KS4 Leavers cohort. 

If you'd like more information on the Sisra Data Collaboration, see our article - What is the Sisra Data Collaboration?

Calculating a student's SPI score

To calculate a student’s SPI in a particular qualification, Analytics looks at all students with the same KS2 prior attainment score in the Sisra collaborative data, as well as their grade points in that specific subject area. Their grade points are then averaged to calculate an overall collaborative average point score. This average is then subtracted from the student’s points score to produce the SPI figure:

For example, the following student has a KS2 average prior attainment score of 96 and has achieved a grade 6 in English Language. So, to calculate this student’s SPI score, Analytics would find the average point score in English Language for all students with the same KS2 prior attainment score (3.24 in 2023) and subtract this from the student’s point score:

6 – 3.24* = 2.76 to 2 decimal places.

*For demonstration purposes only, this would be the average point score calculated from the collaboration data you have published with.

This indicates that the student is performing just under 3 grade points better in this qualification than other students in the collaboration with the same average prior attainment score (96 in this case). The below screenshot is taken from the Grades List report > Student level which shows each student’s SPI figure in the blue Subject Progress Index column, as well as a visual representation in the SPI Chart column.

Calculating Class or Qualification SPI Scores

SPI scores at class or qualification level are calculated by totalling the scores of the students within that class or qualification and dividing this by the number of students included, showing an average SPI for the class or qualification.

This allows you to compare the performance of your classes or qualifications to one another.

Positive SPI

When viewing the Overview or Total reports, you will see a column for Positive SPI. This shows the count or percentage of students based on the report level you’re viewing, that have achieved an SPI score of on or above 0.

SPI Warning Icons

The following icons may also be displayed at Student level, to draw your attention to specific SPI scores, which you may want to consider when analysing the data:

	Caution, one of the following applies: (1) Low cohort in the Data Collaboration (DC) for this qualification (1a) DC data may be grouped with other qualifications. (2) Qualification unapproved in this DC year. This can be due to a qualification having low uptake across schools opted into our Data Collaboration, therefore the data your students’ performance is being compared with may not be as accurate. In some of these cases, we have grouped the qualification with others which closely aligned to make the comparisons more robust. This can also be displayed for new qualifications, which have not yet been reported on within the Data Collaboration event published, or if the qualification was previously unapproved and therefore there is no official data available.
	Difference figure calculated using collaboration data with low student counts. This can be due to the number of students with a particular prior attainment being low enough that the figures may not provide a true indication of progression but can still provide an idea of how the students have performed compared to others with the same prior attainment. The number of students that would cause this icon can vary based on the DC data in use but in 2023 this was between 10-24 students.
	Difference cannot be calculated due to suppression of Collaboration Data / Collaboration Data suppressed due to low student count. This can be due to the number of students with a particular prior attainment being extremely low and so the difference wouldn’t be calculated, as this wouldn’t provide a true indication of progression and no SPI score can be calculated. The number of students that would cause this icon can vary based on the DC data in use but in 2023 this was between 0-9 students.

Thanks for reading!