{
    "original_study": {
        "claim": {
            "hypothesis": "Previous research…suggests that, once controlling for individual and familial background factors, the bilingual students will, on average, have higher scores in English as a foreign language compared to the monolingual group. Therefore we hypothesize similar advantages for the bilingual students in the present sample (Hypothesis 1a).",
            "hypothesis_location": "Section 1: Introduction; Subsection 1.4: Research questions; p. 78-79",
            "statement": "Given comparable individual and familiar background characteristics bilingual group membership is positively associated with English foreign language achievement.",
            "statement_location": "Section 3: Results; Subsection 3.2: Bilingualism and English achievement; p. 80.",
            "study_type": "Observational" 
        },


        "data": {
            "source": "Assessment of Reading and Mathematics Development Study",
            "wave_or_subset": "NA",
            "sample_size": "2946",
            "unit_of_analysis": "Student",
            "access_details": "not stated",
            "notes": "The final sample size (after cleaning) was 2835 students nested in 134 elementary\nschool classes."
        },

        "method": {
            "description": "The authors use regression analysis, controlling for background characteristics, to explore the effect of bilingualism on English language achievement in school.",
            "steps": "(1) Clean the data by keeping only those with language information; (2) the bilingual group was divided into five proficiency groups from a standardized competency scale; (3) construct the English language achievement measure using weighted likelihood estimates (WLEs) for individual person parameters; (4) conducted all analyses using five imputed datasets, in which the missing values were replaced by plausible values.",
            "models": "uncontrolled regression model; regression model including controls",
            "outcome_variable": "English language achievement",
            "independent_variables": "Bilingualism",
            "control_variables": "general cognitive abilities, gender, age, socio-economic status, parental education, and cultural capital",
            "tools_software": "MPlus 5.21"
        },
        "results": {
            "summary": "the bilingual group had a relatively slight advantage (b = 2.68), which can be interpreted as just over a quarter of a school year's achievement.",
            "numerical_results": [
                {
                    "outcome_name": "English achievement",
                    "value": "2.68",
                    "unit": "not stated",
                    "effect_size": "just over a quarter of a school year's achievement",
                    "confidence_interval": {
                        "lower": "not stated",
                        "upper": "not stated",
                        "level": "not stated"
                    },
                    "p_value": "<0.01",
                    "statistical_significance": "1% level",
                    "direction": "Positive"
                }
            ]
        },
       
        "metadata": {
            "original_paper_id": "10.1016/j.learninstruc.2014.12.001.",
            "original_paper_title": "The effect of speaking a minority language at home on foreign language learning.",
            "original_paper_code": "not stated",
            "original_paper_data": "not sated"
        }
    }
}