Did child obesity decline after 2016 food regulations in Chile?

We estimated trends in the prevalence of obesity and overweight among Chilean primary and secondary students before and after Chile's 2016 regulations on the marketing and availability of foods high in energy, total sugars, sodium, or saturated fat. We used data from Chile's Survey of Nutrition, which measured the body mass index (BMI) of students in government-funded schools. Using BMI thresholds defined by the World Health Organization, we calculated the prevalence of overweight and obesity for each year from 2013 to 2019 among students attending pre-kindergarten (age 4 years), kindergarten (age 5 years), first grade (6 years), and ninth grade (14 years).

The effect of smaller classes on infection-related school absence: evidence from the Project STAR randomized controlled trial.

Background: In an effort to reduce viral transmission, many schools reduced class sizes during the recent pandemic. Yet the effect of class size on transmission is unknown.

Methods: We used data from Project STAR, a randomized controlled trial in which 10,816 Tennessee elementary students were assigned at random to smaller classes (13 to 17 students) or larger classes (22 to 26 students) in 1985-89.

Have States Reduced Obesity by Legislating More Physical Activity in Elementary School?

Unlabelled: Policy Points Between 1998 and 2016, 24 states and the District of Columbia passed laws meant to increase the time that children spent in physical education (PE) or other school-based physical activity (PA). Schools largely disregarded changes to PE/PA laws, which did not increase the time that children spent in PE or recess and did not reduce body mass index, overweight, or obesity. Closer oversight of schools would be needed to improve compliance with state PE and PA laws.

Is Kindergarten Ability Group Placement Biased? New Data, New Methods, New Answers.

Half of kindergarten teachers split children into higher and lower ability groups for reading or math. In national data, we predicted kindergarten ability group placement using linear and ordinal logistic regression with classroom fixed effects. In fall, test scores were the best predictors of group placement, but there was bias favoring girls, high-SES (socioeconomic status) children, and Asian Americans, who received higher placements than their scores alone would predict.

Is Psychological Science Self-Correcting? Citations Before and After Successful and Failed Replications.

In principle, successful replications should enhance the credibility of scientific findings, and failed replications should reduce credibility. Yet it is unknown how replication typically affects the influence of research. We analyzed the citation history of 98 articles.

The data revolution comes to higher education: identifying students at risk of dropout in Chile.

Enrolment in higher education has risen dramatically in Latin America, especially in Chile. Yet graduation and persistence rates remain low. One way to improve graduation and persistence is to use data and analytics to identify students at risk of dropout, target interventions, and evaluate interventions' effectiveness at improving student success.

Tonal and "Anti-Tonal" Cognitive Structure in Viennese Twelve-Tone Rows.

We show that the twelve-tone rows of Arnold Schoenberg and Anton Webern are "anti-tonal"-that is, structured to avoid or undermine listener's tonal schemata. Compared to randomly generated rows, segments from Schoenberg's and Webern's rows have significantly lower fit to major and minor key profiles. The anti-tonal structure of Schoenberg's and Webern's rows is still evident when we statistically controlled for their preference for other row features such as mirror symmetry, derived and hexachordal structures, and preferences for certain intervals and trichords.

How Many Imputations Do You Need? A Two-stage Calculation Using a Quadratic Rule.

When using multiple imputation, users often want to know how many imputations they need. An old answer is that 2-10 imputations usually suffice, but this recommendation only addresses the efficiency of point estimates. You may need more imputations if, in addition to efficient point estimates, you also want standard error () estimates that would not change (much) if you imputed the data again.

Missing children: how Chilean schools evaded accountability by having low-performing students miss high-stakes tests.

High-stakes testing pressures schools to raise test scores, but schools respond to pressure in different ways. Some responses produce real, broad increases in learning, but other responses can raise reported test scores without increasing learning. We estimate the effect of an accountability program on reading scores and math scores in Chile.

Does Achievement Rise Fastest with School Choice, School Resources, or Family Resources? Chile from 2002 to 2013.

Debates in education policy draw on different theories about how to raise children's achievement. The theory holds that achievement rises when students can choose among competing schools. The theory holds that achievement rises with schools' resources per student.

Socioeconomic, Ethnic, Racial, and Gender Gaps in Children's Social/Behavioral Skills: Do They Grow Faster in School or out?

Children's social and behavioral skills vary considerably by socioeconomic status (SES), race and/or ethnicity, and gender, yet it is unclear to what degree these differences are due to school or nonschool factors. We observe how gaps in social and behavioral skills change during school and nonschool (summer) periods from the start of kindergarten entry until the end of second grade in a recent and nationally representative sample of more than 16,000 children (the Early Childhood Longitudinal Study Kindergarten Class of 2010-11). We find that large gaps in social and behavioral skills exist at the start of kindergarten entry, and these gaps favor high-SES, white, and female children.

Inequality in Reading and Math Skills Forms Mainly before Kindergarten: A Replication, and Partial Correction, of "Are Schools the Great Equalizer?".

When do children become unequal in reading and math skills? Some research claims that inequality grows mainly before school begins. Some research claims that schools cause inequality to grow. And some research-including the 2004 study "Are Schools the Great Equalizer?"-claims that inequality grows mainly during summer vacations.

How much does teacher quality vary across teacher preparation programs? Reanalyses from six states.

At least sixteen US states have taken steps toward holding teacher preparation programs (TPPs) accountable for teacher value-added to student test scores. Yet it is unclear whether teacher quality differences between TPPs are large enough to make an accountability system worthwhile. Several statistical practices can make differences between TPPs appear larger and more significant than they are.

Understanding differences between summer vs. school obesogenic behaviors of children: the structured days hypothesis.

Background: Although the scientific community has acknowledged modest improvements can be made to weight status and obesogenic behaviors (i.e., physical activity, sedentary/screen time, diet, and sleep) during the school year, studies suggests improvements are erased as elementary-age children are released to summer vacation.

Does more education cause lower BMI, or do lower-BMI individuals become more educated? Evidence from the National Longitudinal Survey of Youth 1979.

More educated adults have lower average body mass index (BMI). This may be due to selection, if adolescents with lower BMI attain higher levels of education, or it may be due to causation, if higher educational attainment reduces BMI gain in adulthood. We test for selection and causation in the National Longitudinal Survey of Youth 1979, which has followed a representative US cohort from age 14-22 in 1979 through age 47-55 in 2012.

Gender and Weight among Thoroughbred Jockeys: Underrepresented Women and Underweight Men.

Discrimination can damage health by limiting an occupation to persons who are physically unsuited to it. In thoroughbred racing, male jockeys damage their health to reach racing weights, while women who could reach those weights more easily are excluded. The authors estimate the number of U.

Better Estimates from Binned Income Data: Interpolated CDFs and Mean-Matching.

Researchers often estimate income statistics from summaries that report the number of incomes in bins such as $0 to 10,000, $10,001 to 20,000, …, $200,000+. Some analysts assign incomes to bin midpoints, but this treats income as discrete. Other analysts fit a continuous parametric distribution, but the distribution may not fit well.

From Kindergarten Through Second Grade, U.S. Children's Obesity Prevalence Grows Only During Summer Vacations.

Objective: To assess the relative importance of school and nonschool risk factors, this study estimated whether overweight and obesity prevalence grows faster during the school year or during summer vacation.

Methods: In the Early Childhood Longitudinal Study, Kindergarten Class of 2010-11, a nationally representative complex random sample of 18,170 U.S.

An education gradient in health, a health gradient in education, or a confounded gradient in both?

There is a positive gradient associating educational attainment with health, yet the explanation for this gradient is not clear. Does higher education improve health (causation)? Do the healthy become highly educated (selection)? Or do good health and high educational attainment both result from advantages established early in the life course (confounding)? This study evaluates these competing explanations by tracking changes in educational attainment and Self-rated Health (SRH) from age 15 to age 31 in the National Longitudinal Study of Youth, 1997 cohort. Ordinal logistic regression confirms that high-SRH adolescents are more likely to become highly educated.

The effects of school physical education grants on obesity, fitness, and academic achievement.

Objective: Foundations and governments fund a number of programs that provide grants to improve school physical education or other forms of school-based physical activity. The effects of these grant programs are unknown. We evaluate the effects of Texas Fitness Now, a program in which the state of Texas granted $37 million to improve physical education in high-poverty middle schools over the 4 school years from 2007-08 to 2010-11.

The heterogeneity statistic I(2) can be biased in small meta-analyses.

Background: Estimated effects vary across studies, partly because of random sampling error and partly because of heterogeneity. In meta-analysis, the fraction of variance that is due to heterogeneity is estimated by the statistic I(2). We calculate the bias of I(2), focusing on the situation where the number of studies in the meta-analysis is small.