org355: School streaming / Zena Stein

Hello everyone - it's been a slow news week, but I spotted this in The Guardian

1. What is the study design?

2. What are the exposure / comparison groups? Who is used as the reference group?

3. What are the outcomes?

4. What mediators have been proposed?

5. The article makes no reference to confounders. Can you suggest one important confounder, and explain why?

6. Could this research question be investigated with a case-control design?

7. Do we need a trial to demonstrate the association is causal? Can you think of one advantage and one disadvantage of doing a trial?

Finally - here's an obituary for Zena Stein in the New York Times.

Re: School streaming / Zena Stein

by | Lena Al-Shammari - Friday, 26 November 2021, 1:11 PM

Thanks, I read this with interest this morning. Pls excuse the over-long answer.

Cross-sectional, cohort study.
Exposure groups: primary school children placed in in-class groups at/after age 7 according to ability
Reference: primary school children not placed in ability groups
Outcomes: peer, emotional, hyperactivity, and behaviour problems up to the age of 14
Mediators: learning dynamics, peer processes, and subtle effects of in-class ability grouping, stigmatisation, or unfavourable social comparisons (& possibly an unmet need for more close monitoring and support of lower-ability groups by teachers)
Confounders:
1. baseline level of hyperactivity, behavioural problems etc - related to the exposure (as if present, that child is probably more likely to be placed in a lower-ability group) and outcome (children with such problems at age 7 are perhaps more likely to suffer from them during the follow-up period).
2. class or group size - it may be that in larger classes, the exposure of ability grouping is more likely to be applied. Also possible that children in larger classes are less likely to receive attention and support, with potentially a greater impact on children in the lower groups (ie it is linked to the outcome, and in a differential way)
Case-control: would involve identifying children with behavioural problems in adolescence, and finding controls who are similar in every other aspect (gender, birth order, prenatal and maternal health, socio-economic status, style and quality of parenting, attendance at pre-school, extra-curricular activity participation....)
No - because difficult to find well-matched controls, and allocation to the ability groupings might be different over time or for different subjects taught.
Trial - would allow for minimising effect on outcome of known and unknown confounders (via randomisation) and being clear about the temporality of the relationship between E and O (giving more info on whether causality is present). However, would likely have LTFU due to the long study period required; would need large sample sizes as it would probably need to be a cluster (+/- stratified) trial.

Re: School streaming / Zena Stein

by | JUDITH MARGARET BURCHARDT - Saturday, 11 December 2021, 10:40 PM

Hi Lena and Sujit,

1. What is the study design?
cohort study

2. What are the exposure / comparison groups? Who is used as the reference group?

children put in top, middle and bottom sets, both between and within classes, with the reference group being children in a mixed ability class

3. What are the outcomes?

peer, emotional, hyperactivity and conduct problems at 7, 11 and 14 years of age

4. What mediators have been proposed?

learning dynamics, peer processes, and subtle effects of in-class ability grouping (thanks to Lena for this)

5. The article makes no reference to confounders. Can you suggest one important confounder, and explain why?

The most obvious confounder would be the school. As the school will be associated both with the exposure (setting) and the outcome (behaviour problems) and is not on the causal pathway between them.

If some schools have more children with behavioural difficulties than others, then they may be more prone to put children into sets than schools where most children are well behaved.

If some schools have year groups with greater ranges of academic ability than others then they may be more prone to put children into sets than schools where most children are of similar ability. It may be more distressing for lower ability children in these schools to observe that they are struggling academically when compared to their peers, and this distress may manifest as behavioural problems.

6. Could this research question be investigated with a case-control design?

It could, but this would not overcome the possibility of reverse causation. I also agree with Lena that it would be difficult to match cases and controls.

7. Do we need a trial to demonstrate the association is causal? Can you think of one advantage and one disadvantage of doing a trial?

An advantage is that a large RCT would be a possible way to investigate causality.
A disadvantage is that it is unlikely that teachers or parents would feel the equipoise needed to run a trial. It also could not be blinded to teachers or students. Researchers assessing behavioural outcomes could be blinded when assessing children, but often they rely on the reports of teachers, students and parents who could not be blinded.

8. Additional points
It seems possible that behavioural problems cause poor academic ability, but this would be reverse causation rather than confounding.
We are not told whether there is a higher proportion of children with behavioural difficulties in the schools with sets or not. If not, then it may be that the sets are organising children by quality of behaviour as well as academic ability. Even if there is a higher proportion of children with behavioural difficulties in schools with sets this may be a confounder as mentioned previously.

Thank you also for letting us know about Zena Stein. What a very likeable and impressive woman. I'm not able to access NY Times articles without paying, but I found a free obituary here

https://www.publichealth.columbia.edu/public-health-now/news/memory-zena-stein-public-health-pioneer-advocate-justice

Best wishes

Judith

Re: School streaming / Zena Stein

by | MADHUTANDRA SARKAR - Thursday, 16 December 2021, 2:03 PM

1. This is a cohort study.
2. The exposure or comparison groups are primary school children placed in in-class groups or between class groups at/after age 7 according to ability, i.e. lower ability group, middle ability group, top ability group and non-group children.
Primary school children not placed in ability groups is used as the reference group.
3. Outcomes are peer, emotional, hyperactivity, and behaviour problems up to the age of 14.
4. The mediators proposed are stigmatisation, or unfavourable social comparisons, etc.
5. The confounder can be family situation. Because a disturbed family can cause impaired ability among children, and it also causes emotional and behavior problems among children and it is not on the causal pathway.
6. This research question can be investigated with a case-control design.
7. We need a trial to demonstrate that the association is causal.
One advantage of doing a trial is less risk of bias and confounding.
One disadvantage is expenses to conduct a trial and a long follow-up period.