Research Article: Child-Staff Ratios in Early Childhood Education and Care Settings and Child Outcomes: A Systematic Review and Meta-Analysis

Date Published: January 19, 2017

Publisher: Public Library of Science

Author(s): Michal Perlman, Brooke Fletcher, Olesya Falenchuk, Ashley Brunsek, Evelyn McMullen, Prakesh S. Shah, Jacobus P. van Wouwe.


Child-staff ratios are a key quality indicator in early childhood education and care (ECEC) programs. Better ratios are believed to improve child outcomes by increasing opportunities for individual interactions and educational instruction from staff. The purpose of this systematic review, and where possible, meta-analysis, was to evaluate the association between child-staff ratios in preschool ECEC programs and children’s outcomes. Searches of Medline, PsycINFO, ERIC, websites of large datasets and reference sections of all retrieved articles were conducted up to July 3, 2015. Cross-sectional or longitudinal studies that evaluated the relationship between child-staff ratios in ECEC classrooms serving preschool aged children and child outcomes were independently identified by two reviewers. Data were independently extracted from included studies by two raters and differences between raters were resolved by consensus. Searches revealed 29 eligible studies (31 samples). Child-staff ratios ranged from 5 to 14.5 preschool-aged children per adult with a mean of 8.65. All 29 studies were included in the systematic review. However, the only meta-analysis that could be conducted was based on three studies that explored associations between ratios and children’s receptive language. Results of this meta-analysis were not significant. Results of the qualitative systematic review revealed few significant relationships between child-staff ratios and child outcomes construed broadly. Thus, the available literature reveal few, if any, relationships between child-staff ratios in preschool ECEC programs and children’s developmental outcomes. Substantial heterogeneity in the assessment of ratios, outcomes measured, and statistics used to capture associations limited quantitative synthesis. Other methodological limitations of the research integrated in this synthesis are discussed.

Partial Text

Early childhood is a critical period in shaping children’s developmental trajectories [1]. Research has shown that high quality early childhood education and care (ECEC) programs can enhance child development [2,3]. Given that enrollment in ECEC settings has become the norm for preschool aged children [4,5], it is important to empirically identify aspects of the ECEC environment that are key in supporting children’s development. Organizations such as the American Academy of Pediatrics (AAP), the American Public Health Association (APHA), the National Institute of Early Education Research (NIEER), and the National Association for the Education of Young Children (NAEYC) have identified indicators of high quality ECEC programs. These guidelines are intended to assist parents, policy makers, funders and other key stakeholders in making informed decisions about ECEC arrangements. The ratio of children to staff is one relatively quantifiable aspect of structural quality identified as a key quality indicator in the AAP’s Policy Statement on Quality Early Education and Child Care [6–10].

The details of the search results and reasons for exclusion of articles are presented in Fig 1. In total, 29 studies met our inclusion criteria; 23 of the studies were peer reviewed journal articles, five were reports and one study reported their results in a book chapter. Descriptive information for the 29 studies is presented in Table 3. Seven studies contained samples that were drawn from both the NCEDL’s Multi-State Study and SWEEP study [20,31–36], three studies were from the CQO project [21,37,38], two studies utilized the Head Start FACES 2000 Cohort sample [39,40], and two studies included samples drawn from the NICHD Study of Early Child Care [15,41]. Furthermore, two studies [42,43] were drawn from the same dataset as were two additional studies using a separate sample of preschool-aged children from Bermuda [44,45]. Thus, many studies had overlapping samples.

Researchers have been examining early childhood education and care settings for decades. Yet, we still lack an acceptable empirically-based directive for stakeholders regarding the effects of quality of care on children’s development [54]. Conclusions concerning which aspects of quality matter most for children are often deduced from a few select intensive early intervention projects conducted in the 1960’s (i.e., The High Scope Perry Preschool Project) and 1970’s (i.e., The Carolina Abecedarian Project). The populations served and scope of services provided in these studies call into question their generalizability and applicability to today’s ECEC programs. In the several decades that have passed since these seminal longitudinal studies were undertaken, extensive research has documented mixed results. We conducted very comprehensive searches that lead to a review of 29 studies. This systematic analysis revealed that within the range of ratios found in the literature, variations in child-staff ratios for pre-school aged children classrooms have small, if any, associations with concurrent or subsequent child outcomes. Ratios showed substantial variability both within the studies that we included and across them. Therefore, the lack of associations between ratios and child outcomes found in our review are not explained by limited ranges of the ratios observed in the samples. Based on the small number of studies available for meta-analysis, no association was found between child-staff ratios and children’s receptive language as measured by the PPVT. However, it is important to note that the studies included in this review only included ratios that met local regulations. Thus, findings from this analysis cannot be used to argue for relaxing existing child-staff ratio regulations.

Despite the substantial limitations of research in this area, the current study suggests that, within the range of permissible child-staff ratios, variations in ratios have small, if any, associations with concurrent and subsequent child outcomes. The small number of significant associations between child-staff ratios in preschool-aged classrooms and children’s developmental outcomes that were reported may reflect selection biases. Specifically, they may reflect family-level factors that play a role in child care selection, such as maternal education or family income, rather than true child care effects. However, as noted above, the research available for this systematic review included studies with significant methodological limitations and only studies with child-staff ratios that fell within current regulations. Thus, our findings should not be interpreted as indicating that regulation of ratios can be relaxed in any way. Rather, we emphasize that within the range of what is currently permissible by licensing regulations, better ratios in preschool-aged ECEC classrooms are not associated with better outcomes for children. This is consistent with findings from large-scale meta-analyses examining teacher-student ratios and student achievement in formal education systems [63]. While we stress that these findings should not be overstated, they do suggest that other areas of investment in quality improvement in ECEC programs, such as staff professional development, may yield better payoffs for the many stakeholders impacted by ECEC quality. In addition, our results indicate a strong need for comparative effectiveness type of research designs on this issue in multiple settings. These include prospective cohorts or cluster randomized studies, with different ratios and prospective criterion-specific evaluations of consumer (parents)-centric outcomes to guide future practice in this area, which affects wide-scale populations.




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