|Perceived birth weight (=1 if low or||||||
|---|---|---|---|---|---|
|verylow)|0.271|0.213|0.202|0.141<br>0.164|0.199|

*Maternal vocabulary represents estimated ability for the Peabody Picture Vocabulary Tests obtained from an item response model.  Ability is reported in log odds units (logit) and ranges between -2 to 2.5 logits.

A comparison of descriptive statistics for the 2011 test scores by wealth quintile is presented in table 2. For all the child development test scores, there is a larger difference in test scores when comparing the middle wealth quintiles relative to the richest quintile (Q5 versus Q3) than from comparing the middle quintile to the poorest one (Q3 versus Q1). Across all age groups, 30% of our 2011 sample of school-age children did not attend school. The percentage of seven-year-olds who are not enrolled in school in our sample is about 50%, decreasing to 13% at age ten years. This pattern of delayed enrollment exhibits important differences across wealth quintiles, with 40% of children in the lowest wealth quintile not in school as opposed to 6% in the highest wealth quintile. Delayed enrollment has been shown to have important economic costs in terms of total grades completed (Alderman et al. 2001; Glewwe and Jacoby 1995). The learning test used in this study is designed to be administered to children both in and out of school; in spite of the fact that the test is supposed to be flexible, performance is highly censored, with three-quarters of the children not attending school reaching a high score of five (median two) in the literacy test as opposed to 40 (median 18) among those attending school (figure A1 in the appendix). As a consequence, wealth gaps in learning outcomes reflect a combination of delayed age of enrollment, as well as performance conditional on enrollment.

Table 2. Descriptive statistics (mean and SD): child development outcomes 2011, by wealth quintile

|||Means|(SD) by q|uintile||Test d|ifference in|means:|
|---|---|---|---|---|---|---|---|---|
||Q1|Q2|Q3|Q4|Q5|Q5-Q3|Q3-Q1|Q5-Q1.|
|Sustained attention z-score|-0.579|-0.233|-0.037|0.189|0.688|-0.728***|-0.540***|-1.268***|
|2011|(0.814)|(0.975)|(0.917)|(0.865)|(0.927)|(0.084)|(0.078)|(0.080)|
|Memory of phrases z-score|-0.569|-0.228|-0.052|0.174|0.687|-0.738***|-0.518***|-1.256***|
|2011|(0.688)|(0.858)|(0.922)|(0.991)|(1.010)|(0.089)|(0.074)|(0.079)|
|Cognition composite z-|-0.587|-0.247|-0.101|0.178|0.753|-0.855***|-0.486***|-1.341***|
|score 2011|(0.680)|(0.837)|(0.878)|(0.962)|(1.031)|(0.088)|(0.072)|(0.081)|
|Vbl 2011|-0.686|-0.297|-0.106|0.226|0.910|-1.016***|-0.580***|-1.596***|
|ocauary z-score|(0.641)|(0.819)|(0.855)|(0.899)|(0.953)|(0.083)|(0.068)|(0.074)|
|Adapted HOME scale|3.657|4.645|5.390|6.081|7.170|-1.77***|-1.74***|-3.51****|
|2011|(2.247)|(2.240)|(2.259)|(2.218)|(1.786)|(0.19)|(0.20)|(0.19)|
|Child unschooled=1 2011<br>(proportion)|0.390|0.324|0.236|0.124|0.065|0.168***|0.157***|0.325***|
|Literacy raw score 2011|2.22|4.40|3.68|2.73|10.20|-6.52**|-1.46*|-7.98***|
|if not in school|(3.64)|(6.45)|(5.05)|(2.85)|(11.26)|(2.08)|(0.81)|<br>(1.64)|
|Literacy raw score 2011|11.50|16.08|20.67|25.47|36.69|-16.05**|-9.17****|-25.19***|
|if in school|(13.72)|(15.89)|(18.07)|(20.42)|(19.39)|(1.87)|(1.82)|(1.89)|
|Lit 2011|-0.591|-0.350|-0.133|0.175|0.813|-0.944***|-0.460***|-1.404***|
|eracy z-score|(0.626)|(0.724)|(0.860)|(1.011)|(1.013)|(0.087)|(0.072)|(0.082)|
|Math raw score 2011|13.78|17.20|19.46|22.21|28.05|-5.85**|-1.20|-7.05***|
|if not in school|(8.23)|(9.19)|(9.24)|(9.59)|(8.75)|(2.14)|(1.04)|(1.70)|