Browsing by Author "San Martin, Ernesto"

Now showing 1 - 8 of 8
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    COMMUNICATIVE CONDITIONS FOR LEARNING IN PRIMARY SCHOOL: A MULTIMODAL, DIALOGIC, AND FUNCTIONAL LOOK AT THE CLASSROOM
    (2016) Medina Morales Lorena Pia; Ortiz, Dominga; Ojeda, Pablo; Alvarado, Constanza; Llanos, Tomas; San Martin, Ernesto; Mansilla, Fernanda; Chova, LG; Martinez, AL; Torres, IC
    The present study was intended to observe and describe the multiple modes of communication employed in the classroom for fostering the learning of students from 7 fifth grades belonging to 3 subsidized private schools in Santiago de Chile, in the areas of Language and Mathematics, during one academic year. This was the specific objective of a wider research project that, by means of a mixed methodology, seeks to establish connections between the communicative conditions of the classroom and students' learning outcomes.
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    Dissecting Chilean surveys: The case of missing outcomes
    (2022) San Martin, Ernesto; Alarcon-Bustamante, Eduardo
    In this paper, the strengths and weaknesses of two Chilean political polls and the National Socioeconomic Characterisation Survey are analyzed from a statistical modelling point of view. The rationale of the analytical strategy is based on a distinction between identified parameters and parameters of interest. This is equivalent to make a distinction between what we can learn from the data provided by a survey and what we want to learn from those data. Using partial identification techniques, each survey is analyzed at different levels according to specific subpopulations. Based on these analyses, we emphasize not only the way in which the results should be reported, but also the necessity to make explicit the uncertainty induced by the non-response rates at the survey report.
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    Identifiability of structural characteristics: How relevant is it for the Bayesian approach?
    (2018) San Martin, Ernesto
    The role of identification in the Bayesian approach is still debatable. Since Lindley [Bayesian Statistics. A Review (1971) Philadelphia], most Bayesian statisticians pretend that unidentifiabiity causes no real difficulty in their approach. Recently, Wechsler, Izbicki and Esteves [Amer. Statist. 67 (2013) 90-93] provide a simple example illustrating this perspective. By critically reading Wechsler, Izbicki and Esteves [Amer. Statist. 67 (2013) 90-93], we intend to show that the Bayesian approach is far from being free of the identification problems, provided that the interest is focused on the interpretation of the parameters. It is written using a rather ancient style, the so-called Platonic dialogues. In modern times, there are beautiful examples of that, particularly in Foundations of Mathematics, where debatable subjects are discussed: let us refer Heyting [Intuitionism. An Introduction (1971) North-Holland Publishing Company], where the debate between a formalist and an intuitionist is presented as a dialogue; or Lakatos [Proofs and Refutations. The Logic of Mathematical Discovery (1976) Cambridge University Press], where the relationship between proofs and conjectures is magnificently illustrated. We hope that this style will help to understand why identifiability really matters in the Bayesian approach.
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    Identification of the 1PL Model with Guessing Parameter: Parametric and Semi-parametric Results
    (2013) San Martin, Ernesto; Rolin, Jean-Marie; Castro, Luis M.
    In this paper, we study the identification of a particular case of the 3PL model, namely when the discrimination parameters are all constant and equal to 1. We term this model, 1PL-G model. The identification analysis is performed under three different specifications. The first specification considers the abilities as unknown parameters. It is proved that the item parameters and the abilities are identified if a difficulty parameter and a guessing parameter are fixed at zero. The second specification assumes that the abilities are mutually independent and identically distributed according to a distribution known up to the scale parameter. It is shown that the item parameters and the scale parameter are identified if a guessing parameter is fixed at zero. The third specification corresponds to a semi-parametric 1PL-G model, where the distribution G generating the abilities is a parameter of interest. It is not only shown that, after fixing a difficulty parameter and a guessing parameter at zero, the item parameters are identified, but also that under those restrictions the distribution G is not identified. It is finally shown that, after introducing two identification restrictions, either on the distribution G or on the item parameters, the distribution G and the item parameters are identified provided an infinite quantity of items is available.
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    Rasch Models: How (In-)Coherently are they Showed and Used?
    (UNIV COSTA RICA, INST INVESTIGACION PSICOLOGICAS, 2015) San Martin, Ernesto
    Rasch models are widely used for the analysis of educational data. In practice, estimates of difficulties of items and abilities of examinees are reported. However, the meaning of the terms "difficulty" and "abilities" are never made explicit. The meaning of these terms does not depend on the estimations; they should be interpreted with respect to the eventual meaning of both item difficulties and individual abilities. This paper shows that the meaning of the terms "difficulty" and "ability" depends on the way in which the Rasch model is specified. In the psychometric literature, Rasch models are specified in two different ways: one specifies the observable only, whereas the other one specifies both observable and unobservable. The first specification is due to Rasch himself, the second one is due to Lord.
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    Temporally Dynamic, Cohort-Varying Value-Added Models
    (2024) Page, Garritt L.; San Martin, Ernesto; Irribarra, David Torres; Van Bellegem, Sebastien
    We aim to estimate school value-added dynamically in time. Our principal motivation for doing so is to establish school effectiveness persistence while taking into account the temporal dependence that typically exists in school performance from one year to the next. We propose two methods of incorporating temporal dependence in value-added models. In the first we model the random school effects that are commonly present in value-added models with an auto-regressive process. In the second approach, we incorporate dependence in value-added estimators by modeling the performance of one cohort based on the previous cohort's performance. An identification analysis allows us to make explicit the meaning of the corresponding value-added indicators: based on these meanings, we show that each model is useful for monitoring specific aspects of school persistence. Furthermore, we carefully detail how value-added can be estimated over time. We show through simulations that ignoring temporal dependence when it exists results in diminished efficiency in value-added estimation while incorporating it results in improved estimation (even when temporal dependence is weak). Finally, we illustrate the methodology by considering two cohorts from Chile's national standardized test in mathematics.
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    The Use of an Identifiability-Based Strategy for the Interpretation of Parameters in the 1PL-G and Rasch Models
    (2019) Farina, Paula; Gonzalez, Jorge; San Martin, Ernesto
    Using the well-known strategy in which parameters are linked to the sampling distribution via an identification analysis, we offer an interpretation of the item parameters in the one-parameter logistic with guessing model (1PL-G) and the nested Rasch model. The interpretations are based on measures of informativeness that are defined in terms of odds of correctly answering the items. It is shown that the interpretation of what is called the difficulty parameter in the random-effects 1PL-G model differs from that of the item parameter in a random-effects Rasch model. It is also shown that the traditional interpretation of the guessing parameter in the 1PL-G model changes, depending on whether fixed-effects or random-effects versions of both models are considered.
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    Voucher system and school effectiveness: Reassessing school performance difference and parental choice decision-making
    (UNIV CHILE DEPT ECONOMICS, 2012) Carrasco, Alejandro; San Martin, Ernesto
    This paper discusses the potential contribution of employing school effectiveness methodological approach within the ongoing research debate on school choice issues. Using the first approach, we estimate the effectiveness of a sample of Chilean schools after controlling by a baseline at the student level. In order to avoid the endogeneity of such a baseline with respect to the school effect, we use a longitudinal data set (SIMCE 2004 and SIMCE 2006) from which a natural pseudo-experiment is defined in such a way that the baseline is by design uncorrelated with the school effect. Thereafter, we investigate possible relationships between parental school choice (as declared in public standardized surveys) and the schools classified by their effectiveness. The main conclusions of this paper are, on the one hand, that there is not remarkable difference between municipal (public) and subsidised schools in terms of their effectiveness analyzed under value-added; and, on the other hand, that there is no relation between parental school choice preferences and school effectiveness.