Under a fixed budget, a higher ICC(1) of the outcome variable shifts the optimal design toward more classes and fewer students per class and reduces maximum power¶
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Evidence · 1 study · theoreticalr3·q2
Currency · newest study 2022 · not yet checked against its sources · not reviewed by a person
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q2 i? The higher the ICC(1) of student achievement, the larger the optimal number of classes, the smaller the optimal number of students per class, and the lower the maximum power to detect the between slope. → Steffen Zitzmann 2021
Evidence¶
Steffen Zitzmann 2021¶
Steffen Zitzmann, Wolfgang Wagner, Martin Hecht, Christoph Helm, Christian Fischer, Lisa Bardach, Richard Göllner. (2021). How Many Classes and Students Should Ideally be Sampled When Assessing the Role of Classroom Climate via Student Ratings on a Limited Budget? An Optimal Design Perspective. Educational Psychology Review (2022) 34:511–536. https://doi.org/10.1007/s10648-021-09635-4
q2 · i? · theoretical · r3
Numerical optimization results shown in Fig. 1 for a fixed budget of 15,000€, costs per class of 100€, costs per student of 10€, ICC(1) of ratings .2, and standardized slopes of .2. The article reports that "a higher ICC(1) will reduce the power to detect the between slope."
"the higher the ICC(1) is (when all other quantities are held constant), the larger the optimal number of classes will be, and the smaller the optimal number of students per class will be."
Discussion¶
Related Claims¶
- The variability of the between slope estimate in the multilevel latent covariate model decreases with more classes and students, with higher ICC(1) of the ratings and larger slopes, but increases with higher ICC(1) of the outcome — related
- A higher ICC(1) of students' ratings and a larger standardized between slope increase power, with opposite effects on the optimal split between classes and students per class — related
- In the PIRLS 2006 teaching-quality example, the optimal fixed-budget design was 395 classes with 12 students per class, and the actual PIRLS design achieved 83% power — related
Page metadata
| Field | Value |
|---|---|
type |
claim |
id |
higher-outcome-icc1-shifts-optimal-design-toward-classes |
title |
Under a fixed budget, a higher ICC(1) of the outcome variable shifts the optimal design toward more classes and fewer students per class and reduces maximum power |
description |
Under a fixed budget, a higher ICC(1) of the outcome variable shifts the optimal design toward more classes and fewer students per class and reduces maximum power |
status |
review |
evidence_strength |
weak |
newest_evidence |
2022 |
generated |
by process:wiki-ingest on 2026-10-21 |
trust |
unverified — no one has confirmed this page's content |
sources |
1 — steffen-zitzmann-2021 |
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