As debate grows over the vital task of teacher assessment for the 2020 exam series, some sensitive arguments will emerge about fairness, selection & biasing some children over another.

It isn’t unprofessional to suggest teachers can be biased; to be biased is to be human. /1 https://twitter.com/ofqual/status/1243254400593866755

Some biases that attend teacher assessment are more challenging than others. It is good to try & scrutinise the best available evidence & avoid personal arguments. @profsimonb et al. showed we can be biased for & against ethnic minorities: http://www.bristol.ac.uk/media-library/sites/cmpo/migrated/documents/wp221.pdf. We can bias /2

Children positively, so teachers could unconsciously bias grade Chinese students & Indian students positively, but Black African or Black Caribbean children negatively. Ethnicity also interplays with biases related to gender. Gender stereotyping begins in early childhood in /3

Countless implicit & explicit ways (see this review: https://bit.ly/2wQB3ShThe ). The evidence can be mixed too: so it may show biases against girls in mathematics (see: https://journals.sagepub.com/doi/10.3102/0013189X19890577), or against boys in maths: https://mitili.mit.edu/sites/default/files/project-documents/SEII-Discussion-Paper-2016.07-Terrier.pdf. What is clear: bias exists /4

Broadly, good evidence suggests a pattern. A study based on the Millenium Conort - ‘Stereotyped at 7?’ (See: https://bit.ly/3aJFKvH ) & a meta-analysis on bias in grading (see: https://bit.ly/34a1Jt9 ) suggest the following are subject to biases: ethnicity, gender, having a /5

SEN label, disadvantage/social status, are all prone to stereotyping that leads to bias in grading & ranking. It is not a self-fulfilling prophecy: school cohorts & practices will mean bias will vary. But bias will exist. This is one key reason why standardised tests are so /6

Valuable, at school level & nationally, though they are easy to fire shots at in the name of improving education. We should accept we are human & attempt to make the best job of teacher assessment & ranking. @mrbakerphysics has a great blog on ranking: https://bit.ly/2yriLXY  /7

There is no simple answer. Schools will no doubt do their best to set up fair processes, mitigating biases, whilst talking about them sensitively. Teachers are biased, like the rest of us, but they are also skilled professionals who will do their best to undertake a fair ranking.