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. We merged Project STAR schools with data on local deaths from pneumonia and influenza in the 122 Cities Mortality Report System. Using mixed effects linear, Poisson, and negative binomial regression, we estimated the main effect of smaller classes on absence. We used an interaction to test whether the effect of small classes on absence was larger when and where community pneumonia and influenza prevalence was high. RESULTS: Small classes reduced absence by 0.43 days/year (95% CI -0.06 to -0.80, p < 0.05), but small classes had no significant interaction with community pneumonia and influenza mortality (95% CI -0.27 to + 0.30, p > 0.90), indicating that the reduction in absence due to small classes was not larger when community disease prevalence was high. CONCLUSION: Small classes reduced absence, but the reduction was not larger when disease prevalence was high, so the reduction in absence was not necessarily achieved by reducing infection. Small classes, by themselves, may not suffice to reduce the spread of respiratory viruses.

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). In ninth grade students, overweight and obesity prevalence rose by 2 percentage points over the 3 years after introduction of the 2016 regulations. In pre-kindergarten, kindergarten, and first grade, overweight and obesity fell 1 to 3 percentage points 1 year after the regulations were introduced, but rebounded to previous levels the next year. Chile's food regulations were not followed by a sustained decline in obesity in primary- and secondary-school students. Future research should examine whether and how children in Chile and other countries maintain high levels of overweight and obesity despite food regulations designed to reduce consumption of obesogenic foods and beverages.

Se estimaron las tendencias en la prevalencia de la obesidad y el sobrepeso en estudiantes chilenos de educación primaria y secundaria, antes y después de las regulaciones introducidas en Chile en el 2016 sobre la comercialización y disponibilidad de productos hipercalóricos, con un alto contenido de azúcares, sodio o grasas saturadas. Se utilizaron datos del Mapa Nutricional de Chile, una encuesta en la que se midió el índice de masa corporal (IMC) de la población estudiantil de las escuelas públicas. Tomando los umbrales de IMC definidos por la Organización Mundial de la Salud, se calculó la prevalencia del sobrepeso y la obesidad para cada año entre el 2013 y el 2019 en estudiantes de jardín de infancia (4 años), preescolar (5 años), primer grado (6 años) y noveno grado (14 años). En los estudiantes de noveno grado, la prevalencia del sobrepeso y la obesidad aumentó en 2 puntos porcentuales durante los 3 años posteriores a la introducción de las regulaciones del 2016. En el caso de los grupos de jardín de infancia, preescolar y primer grado, el sobrepeso y la obesidad disminuyeron entre 1 y 3 puntos porcentuales un año después de la introducción de las regulaciones, pero al año siguiente volvieron a los niveles anteriores. La introducción de las regulaciones alimentarias de Chile no estuvo seguida de una disminución continua de la obesidad en la población estudiantil de primaria y secundaria. En las investigaciones futuras se deberá examinar si la población infantil de Chile y otros países mantiene niveles altos de sobrepeso y obesidad a pesar de las regulaciones alimentarias diseñadas para reducir el consumo de productos y bebidas obesogénicos, así como las características específicas que adopta este problema de salud.

Foram estimadas tendências de prevalência da obesidade e do sobrepeso em alunos chilenos do ensino fundamental e médio antes e depois da regulamentação de 2016 da propaganda e disponibilidade de alimentos com alto teor calórico ou ricos em açúcares totais, sódio ou gorduras saturadas no Chile. Foram utilizados dados obtidos da Pesquisa em Nutrição do Chile, que aferiu o índice de massa corporal (IMC) de escolares da rede pública. Com base nos limiares de IMC definidos pela Organização Mundial da Saúde (OMS), calculou-se a prevalência anual de sobrepeso e obesidade em crianças na pré-escola (4 anos), no jardim da infância (5 anos), no primeiro ano (6 anos) e no nono ano (14 anos) em cada ano no período entre 2013 e 2019. Entre os alunos do nono ano, a prevalência de sobrepeso e obesidade aumentou 2 pontos percentuais nos 3 anos que se seguiram à introdução da regulamentação de 2016. Entre os alunos da pré-escola, do jardim de infância e do primeiro ano, ocorreu uma redução de 1 a 3 pontos percentuais na prevalência de sobrepeso e obesidade um ano após a introdução da regulamentação, mas os níveis voltaram a subir no ano seguinte. A regulamentação de alimentos não resultou em um declínio sustentado da obesidade nos alunos do ensino fundamental e médio do Chile. Pesquisas futuras devem ser realizadas para avaliar se, e como, a prevalência de sobrepeso e obesidade nas crianças chilenas e de outros países se mantém alta a despeito da regulamentação de alimentos visando à redução do consumo de alimentos e bebidas obesogênicos.

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

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. Yet, even with better compliance, we estimate that PE and PA policies would be inadequate to reverse the obesity epidemic. Policies should also address consumption, both inside and outside of school. CONTEXT: To control childhood obesity, leading medical organizations have recommended increasing the time that children spend in physical education (PE) and other school-based physical activity (PA). Yet, it is unknown how many states have passed laws that codify these recommendations, and it is unknown what effect changing state laws has had on obesity or the time that children actually spent in PE and PA. METHODS: We joined state laws to national samples of 13,920 children from two different cohorts of elementary students. One cohort attended kindergarten in 1998; the other attended kindergarten in 2010; both cohorts were followed from kindergarten through fifth grade. We estimated the effects of changes to state laws in a regression with state and year fixed effects. FINDINGS: Twenty-four states and the District of Columbia increased the time that children were recommended or required to spend in PE or PA. These changes in state policies did not increase actual time spent in PE or recess, did not affect average body mass index (BMI) or BMI Z score, and did not affect the prevalence of overweight or obesity. CONCLUSION: Increasing the PE or PA time required or recommended by state laws has not slowed the obesity epidemic. Many schools have failed to comply with state laws. A back-of-the-envelope calculation suggests that, even with better compliance, the legislated changes in PE laws might not have changed energy balance enough to reduce obesity prevalence.

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. Net of SES, there was no bias against placing black children in higher groups. By spring, one third of kindergartners moved groups, and high-SES children moved up more than their score gains alone would predict. Teacher-reported behaviors (e.g., attentiveness, approaches to learning) helped explain girls' higher placements, but did little to explain the higher placements of Asian American and high-SES children.

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. We illustrate the potential of this approach using data from eight Chilean universities. Results show that data available at matriculation are only weakly predictive of persistence, while prediction improves dramatically once data on university grades become available. Some predictors of persistence are under policy control. Financial aid predicts higher persistence, and being denied a first-choice major predicts lower persistence. Student success programmes are ineffective at some universities; they are more effective at others, but when effective they often fail to target the highest risk students. Universities should use data regularly and systematically to identify high-risk students, target them with interventions, and evaluate those interventions' effectiveness.

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 (SE) estimates that would not change (much) if you imputed the data again. For replicable SE estimates, the required number of imputations increases quadratically with the fraction of missing information (not linearly, as previous studies have suggested). I recommend a two-stage procedure in which you conduct a pilot analysis using a small-to-moderate number of imputations, then use the results to calculate the number of imputations that are needed for a final analysis whose SE estimates will have the desired level of replicability. I implement the two-stage procedure using a new SAS macro called %mi_combine and a new Stata command called how_many_imputations.

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 school competition theory holds that achievement rises when students can choose among competing schools. The school resources theory holds that achievement rises with schools' resources per student. The family resources theory holds that achievement rises as parents become more educated and earn higher incomes. We test all three theories in Chile between 2002 and 2013, when reading and math scores rose by 0.2 to 0.3 standard deviations, as school competition, school resources, and family resources all increased. We compare Chilean municipalities in a difference-in-differences analysis, asking whether test scores rose fastest in municipalities with greater increases in school competition, school resources, or family resources. We find that municipal test scores did not rise with school competition but did rise with family resources (parental education, not income) and, to a smaller extent, with school resources (as measured by class sizes). Results favor the family resource theory, and to a lesser extent the school resource theory, but not the school competition theory.

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. Unfortunately, the test scores used in the Great Equalizer study suffered from a measurement artifact that exaggerated estimates of inequality growth. In addition, the Great Equalizer study is dated and its participants are no longer school-aged. In this article, we replicate the Great Equalizer study using better test scores in both the original data and a newer cohort of children. When we use the new test scores, we find that variance is substantial at the start of kindergarten and does not grow but actually shrinks over the next two to three years. This finding, which was not evident in the original Great Equalizer study, implicates the years before kindergarten as the primary source of inequality in elementary reading and math. Total score variance grows during most summers and shrinks during most school years, suggesting that schools reduce inequality overall. Changes in inequality are small after kindergarten and do not replicate consistently across grades, subjects, or cohorts. That said, socioeconomic gaps tend to shrink during the school year and grow during the summer, while the black-white gap tends to follow the opposite pattern.

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. We reanalyze TPP evaluations from 6 states-New York, Louisiana, Missouri, Washington, Texas, and Florida-using appropriate methods implemented by our new caterpillar command for Stata. Our results show that teacher quality differences between most TPPs are negligible-.01-0.03 standard deviations in student test scores-even in states where larger differences were reported previously. While ranking all a state's TPPs is not useful, in some states and subjects we can find a single TPP whose teachers are significantly above or below average. Such exceptional TPPs may reward further study.

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. Emerging evidence shows children return to school after summer vacation displaying accelerated weight gain compared to the weight gained occurring during the school year. Understanding how summer days differ from when children are in school is, therefore, essential. DISCUSSION: There is limited evidence on the etiology of accelerated weight gain during summer, with few studies comparing obesogenic behaviors on the same children during school and summer. For many children, summer days may be analogous to weekend days throughout the school year. Weekend days are often limited in consistent and formal structure, and thus differ from school days where segmented, pre-planned, restrictive, and compulsory components exist that shape obesogenic behaviors. The authors hypothesize that obesogenic behaviors are beneficially regulated when children are exposed to a structured day (i.e., school weekday) compared to what commonly occurs during summer. This is referred to as the 'Structured Days Hypothesis' (SDH). To illustrate how the SDH operates, this study examines empirical data that compares weekend day (less-structured) versus weekday (structured) obesogenic behaviors in U.S. elementary school-aged children. From 190 studies, 155 (~80%) demonstrate elementary-aged children's obesogenic behaviors are more unfavorable during weekend days compared to weekdays. CONCLUSION: In light of the SDH, consistent evidence demonstrates the structured environment of weekdays may help to protect children by regulating obesogenic behaviors, most likely through compulsory physical activity opportunities, restricting caloric intake, reducing screen time occasions, and regulating sleep schedules. Summer is emerging as the critical period where childhood obesity prevention efforts need to be focused. The SDH can help researchers understand the drivers of obesogenic behaviors during summer and lead to innovative intervention development.

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 stated goals of Texas Fitness Now were to reduce obesity, increase fitness, and raise academic achievement. METHOD: We summarize how Texas Fitness Now funds were spent and estimate the impact of Texas Fitness Now using a fixed-effects longitudinal model that exploits changes in schools' eligibility over time. Changes in eligibility occurred when eligibility expanded to new schools after year 2 and when the program was terminated after year 4. RESULTS: Most Texas Fitness Now funds were spent on sports and fitness equipment. Smaller amounts were spent on anti-obesity curricula. Texas Fitness Now improved strength and flexibility, especially among girls, but it did not improve BMI or academic achievement, and it had mixed effects on aerobic capacity. The fitness benefits were not lost in the year after the program ended, perhaps because schools kept the equipment that they had bought during their years of eligibility. CONCLUSION: The results of Texas Fitness Now were typical for an intervention that relied almost exclusively on physical activity. Programs that improve BMI as well as fitness tend to have a more fully developed nutrition component.

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. Small meta-analyses are common; in the Cochrane Library, the median number of studies per meta-analysis is 7 or fewer. METHODS: We use Mathematica software to calculate the expectation and bias of I(2). RESULTS: I(2) has a substantial bias when the number of studies is small. The bias is positive when the true fraction of heterogeneity is small, but the bias is typically negative when the true fraction of heterogeneity is large. For example, with 7 studies and no true heterogeneity, I(2) will overestimate heterogeneity by an average of 12 percentage points, but with 7 studies and 80 percent true heterogeneity, I(2) can underestimate heterogeneity by an average of 28 percentage points. Biases of 12-28 percentage points are not trivial when one considers that, in the Cochrane Library, the median I(2) estimate is 21 percent. CONCLUSIONS: The point estimate I(2) should be interpreted cautiously when a meta-analysis has few studies. In small meta-analyses, confidence intervals should supplement or replace the biased point estimate I(2).

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. Each was published by a selective psychology journal in 2008 and subjected to a replication attempt published in 2015. Relative to successful replications, failed replications reduced citations of replicated studies by only 5% to 9% on average, an amount that did not differ significantly from zero. Less than 3% of articles citing the original studies cited the replication attempt. It does not appear that replication failure much reduced the influence of nonreplicated findings in psychology. To increase the influence of replications, we recommend (a) requiring authors to cite replication studies alongside the individual findings and (b) enhancing reference databases and search engines to give higher priority to replication studies.

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. Over a 6-year period, fourth-grade reading and math scores rose by 0.2 to 0.3 standard deviations, on average, and half the rise was due to the accountability program. However, many schools, especially schools serving disadvantaged students, inflated their accountability ratings by having low-performing students miss high-stakes tests. To encourage healthier responses to accountability, we recommend setting accountability goals that are attainable for schools with disadvantaged students, and providing incentives for all students to take high-stakes tests.

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. The twelve-tone composer Alban Berg, by contrast, often wrote rows with segments that fit major or minor keys quite well.

Did child obesity decline after 2016 food regulations in Chile? / ¿Disminuyó la obesidad infantil en Chile después de la introducción de las regulaciones alimentarias en el 2016? / A obesidade infantil diminuiu após a regulamentação de alimentos de 2016 no Chile?

[ABSTRACT]. 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). In ninth grade students, overweight and obesity prevalence rose by 2 percentage points over the 3 years after introduction of the 2016 regulations. In pre-kindergarten, kindergarten, and first grade, overweight and obesity fell 1 to 3 percentage points 1 year after the regulations were introduced, but rebounded to previous levels the next year. Chile’s food regulations were not followed by a sustained decline in obesity in primary- and secondary-school students. Future research should examine whether and how children in Chile and other countries maintain high levels of overweight and obesity despite food regulations designed to reduce consumption of obesogenic foods and beverages.

[RESUMEN]. Se estimaron las tendencias en la prevalencia de la obesidad y el sobrepeso en estudiantes chilenos de educación primaria y secundaria, antes y después de las regulaciones introducidas en Chile en el 2016 sobre la comercialización y disponibilidad de productos hipercalóricos, con un alto contenido de azúcares, sodio o grasas saturadas. Se utilizaron datos del Mapa Nutricional de Chile, una encuesta en la que se midió el índice de masa corporal (IMC) de la población estudiantil de las escuelas públicas. Tomando los umbrales de IMC definidos por la Organización Mundial de la Salud, se calculó la prevalencia del sobrepeso y la obesidad para cada año entre el 2013 y el 2019 en estudiantes de jardín de infancia (4 años), preescolar (5 años), primer grado (6 años) y noveno grado (14 años). En los estudiantes de noveno grado, la prevalencia del sobrepeso y la obesidad aumentó en 2 puntos porcentuales durante los 3 años posteriores a la introducción de las regulaciones del 2016. En el caso de los grupos de jardín de infancia, preescolar y primer grado, el sobrepeso y la obesidad disminuyeron entre 1 y 3 puntos porcentuales un año después de la introducción de las regulaciones, pero al año siguiente volvieron a los niveles anteriores. La introducción de las regulaciones alimentarias de Chile no estuvo seguida de una disminución continua de la obesidad en la población estudiantil de primaria y secundaria. En las investigaciones futuras se deberá examinar si la población infantil de Chile y otros países mantiene niveles altos de sobrepeso y obesidad a pesar de las regulaciones alimentarias diseñadas para reducir el consumo de productos y bebidas obesogénicos, así como las características específicas que adopta este problema de salud.

[RESUMO]. Foram estimadas tendências de prevalência da obesidade e do sobrepeso em alunos chilenos do ensino fundamental e médio antes e depois da regulamentação de 2016 da propaganda e disponibilidade de alimentos com alto teor calórico ou ricos em açúcares totais, sódio ou gorduras saturadas no Chile. Foram utilizados dados obtidos da Pesquisa em Nutrição do Chile, que aferiu o índice de massa corporal (IMC) de escolares da rede pública. Com base nos limiares de IMC definidos pela Organização Mundial da Saúde (OMS), calculou-se a prevalência anual de sobrepeso e obesidade em crianças na pré-escola (4 anos), no jardim da infância (5 anos), no primeiro ano (6 anos) e no nono ano (14 anos) em cada ano no período entre 2013 e 2019. Entre os alunos do nono ano, a prevalência de sobrepeso e obesidade aumentou 2 pontos percentuais nos 3 anos que se seguiram à introdução da regulamentação de 2016. Entre os alunos da pré-escola, do jardim de infância e do primeiro ano, ocorreu uma redução de 1 a 3 pontos percentuais na prevalência de sobrepeso e obesidade um ano após a introdução da regulamentação, mas os níveis voltaram a subir no ano seguinte. A regulamentação de alimentos não resultou em um declínio sustentado da obesidade nos alunos do ensino fundamental e médio do Chile. Pesquisas futuras devem ser realizadas para avaliar se, e como, a prevalência de sobrepeso e obesidade nas crianças chilenas e de outros países se mantém alta a despeito da regulamentação de alimentos visando à redução do consumo de alimentos e bebidas obesogênicos.

Did child obesity decline after 2016 food regulations in Chile? / ¿Disminuyó la obesidad infantil en Chile después de la introducción de las regulaciones alimentarias en el 2016? / A obesidade infantil diminuiu após a regulamentação de alimentos de 2016 no Chile?

ABSTRACT 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). In ninth grade students, overweight and obesity prevalence rose by 2 percentage points over the 3 years after introduction of the 2016 regulations. In pre-kindergarten, kindergarten, and first grade, overweight and obesity fell 1 to 3 percentage points 1 year after the regulations were introduced, but rebounded to previous levels the next year. Chile's food regulations were not followed by a sustained decline in obesity in primary- and secondary-school students. Future research should examine whether and how children in Chile and other countries maintain high levels of overweight and obesity despite food regulations designed to reduce consumption of obesogenic foods and beverages.

RESUMEN Se estimaron las tendencias en la prevalencia de la obesidad y el sobrepeso en estudiantes chilenos de educación primaria y secundaria, antes y después de las regulaciones introducidas en Chile en el 2016 sobre la comercialización y disponibilidad de productos hipercalóricos, con un alto contenido de azúcares, sodio o grasas saturadas. Se utilizaron datos del Mapa Nutricional de Chile, una encuesta en la que se midió el índice de masa corporal (IMC) de la población estudiantil de las escuelas públicas. Tomando los umbrales de IMC definidos por la Organización Mundial de la Salud, se calculó la prevalencia del sobrepeso y la obesidad para cada año entre el 2013 y el 2019 en estudiantes de jardín de infancia (4 años), preescolar (5 años), primer grado (6 años) y noveno grado (14 años). En los estudiantes de noveno grado, la prevalencia del sobrepeso y la obesidad aumentó en 2 puntos porcentuales durante los 3 años posteriores a la introducción de las regulaciones del 2016. En el caso de los grupos de jardín de infancia, preescolar y primer grado, el sobrepeso y la obesidad disminuyeron entre 1 y 3 puntos porcentuales un año después de la introducción de las regulaciones, pero al año siguiente volvieron a los niveles anteriores. La introducción de las regulaciones alimentarias de Chile no estuvo seguida de una disminución continua de la obesidad en la población estudiantil de primaria y secundaria. En las investigaciones futuras se deberá examinar si la población infantil de Chile y otros países mantiene niveles altos de sobrepeso y obesidad a pesar de las regulaciones alimentarias diseñadas para reducir el consumo de productos y bebidas obesogénicos, así como las características específicas que adopta este problema de salud.

RESUMO Foram estimadas tendências de prevalência da obesidade e do sobrepeso em alunos chilenos do ensino fundamental e médio antes e depois da regulamentação de 2016 da propaganda e disponibilidade de alimentos com alto teor calórico ou ricos em açúcares totais, sódio ou gorduras saturadas no Chile. Foram utilizados dados obtidos da Pesquisa em Nutrição do Chile, que aferiu o índice de massa corporal (IMC) de escolares da rede pública. Com base nos limiares de IMC definidos pela Organização Mundial da Saúde (OMS), calculou-se a prevalência anual de sobrepeso e obesidade em crianças na pré-escola (4 anos), no jardim da infância (5 anos), no primeiro ano (6 anos) e no nono ano (14 anos) em cada ano no período entre 2013 e 2019. Entre os alunos do nono ano, a prevalência de sobrepeso e obesidade aumentou 2 pontos percentuais nos 3 anos que se seguiram à introdução da regulamentação de 2016. Entre os alunos da pré-escola, do jardim de infância e do primeiro ano, ocorreu uma redução de 1 a 3 pontos percentuais na prevalência de sobrepeso e obesidade um ano após a introdução da regulamentação, mas os níveis voltaram a subir no ano seguinte. A regulamentação de alimentos não resultou em um declínio sustentado da obesidade nos alunos do ensino fundamental e médio do Chile. Pesquisas futuras devem ser realizadas para avaliar se, e como, a prevalência de sobrepeso e obesidade nas crianças chilenas e de outros países se mantém alta a despeito da regulamentação de alimentos visando à redução do consumo de alimentos e bebidas obesogênicos.