Staffing Ratios Effect on Childcare Quality and Child Outcomes in the Light of Denmark’s Minimum Standards: A Meta-Systematic Literature Review of International and Scandinavian Evidence

Summary

The early childhood education and care (ECEC) sector is widely recognized for its developmental, economic, and social significance, particularly in reducing socioeconomic inequalities and fostering children’s skill development. Denmark has a high enrollment rate and relatively high expenditure on ECEC compared to other countries, and the country has implemented reforms establishing minimum staff–child ratio requirements. These stipulate that there must be at least one adult per three children in nurseries and one adult per six children in kindergartens. The aim of these policy initiatives is to strengthen quality in ECEC, but it remains unclear to what extent research documents that improved ratios genuinely increase quality, and whether they have a measurable effect on children’s development. It is also relevant to assess whether research-based evidence supports the established minimum requirements.

To shed light on these questions, this article conducts a systematic review of existing evidence, represented by systematic reviews, meta-analyses, and scoping reviews. The analysis focuses on the significance of staff–child ratios for quality in ECEC, children’s cognitive, socio-emotional, and academic outcomes, and whether empirical evidence can help assess and support the scope of the established minimum ratios.

The review shows that while some studies suggest that lower numbers of children per adult can improve developmental outcomes, the results are highly context-dependent and thus inconsistent. Methodological challenges, such as heterogeneity, ecological validity, and the lack of causal estimates, complicate clear conclusions. More experimental studies are needed, especially focusing on younger children, optimal ratios, and perspectives that extend beyond staffing levels alone.

Research highlights the importance of appropriate ratios in ECEC, but the overall evidence does not unambiguously support the notion that better ratios consistently increase quality or improve child development. This points to a complex interplay between structural and process-related factors. A cross-sectional analysis of Scandinavian and international studies reveals notable differences: Danish researchers generally recommend fewer children per adult, while international studies show mixed results. Qualitative studies emphasize the negative consequences of insufficient ratios, while quantitative evidence remains too ambiguous and insufficient to draw firm conclusions.

The analysis underscores the need for more empirically robust research that can serve as a foundation for evidence-based policy decisions on ratios, particularly with a view to optimizing resource use and improving quality in ECEC. Research should especially examine the interplay between ratios, staff qualifications, and pedagogical practice, as well as include cost–benefit analyses of improvements in ratios to support sustainable and high-quality ECEC practices.

Overall, the existing evidence does not provide a clear basis for fixed minimum ratios, and the current standards function more as normative benchmarks than as minimum requirements supported by the broader body of international research evidence.

Perspectives on the analysis results

The review of research on ratios and quality in early childhood institutions points to many factors other than ratios as pathways to achieving quality improvements in ECEC. Teachers’ professional competencies, leadership, and daily pedagogical practice often play an equally important—or even greater—role.

This does not mean that ratios are entirely irrelevant. For example, very poor ratios can have negative effects, and good ratios combined with well-educated staff can have positive effects. But ratios alone do not solve the quality issues facing Denmark. The effect depends on how resources are used—and especially on who occupies the positions. Hiring more adults does not increase quality if they lack the necessary pedagogical expertise.

Educational research provides evidence that staff education and professional development, strong pedagogical leadership, and targeted professional practice positively impact quality in early childhood institutions. The effect of these parameters naturally interacts with ratios—but ratios are not the main driver.

A strong and overly one-sided political focus on staffing ratios risks overshadowing other crucial quality factors—such as continuing education, pedagogical development work, and leadership development. If a narrow focus on ratio figures comes at the expense of professional expertise, continuing education, and institutional development, there is a risk of wasting significant allocated resources. In some of the most disadvantaged institutions with low quality, the challenges are not clearly a matter of ratios. How would a municipal-level minimum ratio actually improve these institutions? This applies, for instance, in larger municipalities where minimum ratios are already met, but where several institutions still have a high proportion of vulnerable children, low quality, and receive remarks from inspections.

Therefore, the results of this analysis should raise significant concern regarding the one-sided political focus on staffing ratios, and the findings may hopefully contribute to a more nuanced political debate on the use of resources in the ECEC sector and what truly creates quality in children’s everyday lives.

To avoid one-sided and erroneous assumptions and priorities in the future, we should ask ourselves a number of questions about what has created the excessive focus on ratios in the Danish ECEC debate. Is it because ratios are easy to communicate politically, since “more hands” are intuitively perceived as a guarantee of higher quality? Is the prominent position of ratios in the debate supported by institutional and political incentives, including professional and interest organizations’ political agendas? Are Danish ECEC researchers to some extent influenced by these political and institutional preferences—preferences that may open access to research funding—and are their assessments of international research therefore somewhat too positive?

At the same time, it is necessary to improve research so it can generate clearer evidence and empirical documentation showing which measures actually contribute to quality and children’s development in ECEC, as well as how the allocated resources can be used most effectively.