We also observe disparities in home learning environments (consistent with H2) and in preprimary quality (consistent with H3). There are socio-economic differences in children’s home stimulation and components of their pre-primary education experience (including environment and teacher attitudes). Children who experience lower-quality home learning environments also experience lower-quality pre-primary education in some regards, but not all. Inequities are largest for structural quality (the pre-primary physical environment), whereas there is less inequity in process quality (teacher practices, children’s experience of quality materials, and adherence to the curriculum).

# **_5.2 Limitations_**

Our results indicate important disparities in ECD, home stimulation, and some aspects of preprimary quality and inputs that are critical to address. However, there are a number of limitations to our results that must be kept in mind and point to important areas for future work and research. First, we were only able to estimate correlations between SES, outcomes, and inputs. The causal effects of inputs, particularly pre-primary inputs, in LMICs are under-researched and an important area for future work. Second, we were comparing one measure of home stimulation to multiple dimensions of pre-primary quality. There may be other aspects of the home environment that we were not able to observe that are more or less unequal. Measuring quality of home stimulation or pre-primary learning environments is quite challenging, as is measuring the learning and development of young children (Burchinal, 2018). Ongoing efforts to improve measurement of ECD and early environments may reveal additional variation in inequality. Additionally, we do not know if one type of input (home or pre-primary, or a particular aspect of pre-primary quality) is more important than another in determining ECD.

Our analyses are based on a sample of pre-primary students. Not all children in Egypt attend preprimary; indeed, there is substantial socio-economic inequality in access to pre-primary (El-Kogali & Krafft, 2015). In the general population of pre-primary aged children (including those not attending pre-primary), there may be different patterns of inequality in home environments. The children not enrolled in pre-primary might particularly benefit from pre-primary or might particularly suffer from low-quality or inequitable pre-primary if they attended pre-primary; our research is not able to assess these dynamics, and they remain an important area for future research.

The sample we used from Egypt was designed to be nationally representative of pre-primary students, however, there was substantial non-response in the parental sample, which we use to measure SES. As Table 3, in the appendix, shows, there are some differences between our parental sample and a nationally representative sample of parents of KG students. The respondents in our sample were of slightly higher SES. This bias in the sample will not necessarily bias our research questions on SES unless there is a differential relationship among the respondents.

Our data collection efforts were also in late 2021, during the ongoing COVID-19 pandemic. While children were again attending pre-primary in person, the pandemic may have affected outcomes in complex ways that we are unable to unpack. These results do not necessarily generalize to other contexts, although future research should investigate the relative role of pre-primary and home environments in other LMICs.

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