This study systematically reviews randomly selected 155 experimental studies in education field originated in the Republic of Turkey between 2010 and 2020. Indiscriminate choice of sample size in recent publications prompted us to evaluate their statistical power and precision. First, above and beyond our review, we could not identify any large-scale experiments such as cluster-randomized or multisite randomized trials, which overcome shortcomings of small-scale experiments, better suit to the organizational structure of the education field, nevertheless require far greater effort and financial resources. Second, none of the small-scale experiments has reported or conducted ex-ante power analysis. Third, results indicate that studies are sufficiently powered to detect medium effects and above (Cohen's d ≥ 0.50), however they are underpowered to detect small effects (Cohen's d ≤ 0.20). Trends in the past ten years indicate precision remained unchanged. We made several recommendations to increase the precision of experimental designs and improve their evidential values: Determine sample size prior to an experiment with power analysis routine, randomize subjects / clusters to obtain unbiased estimates, collect pre-test information and other relevant covariates, adjust for baseline differences beyond covariate control, document attrition, report standardized treatment effect and standardized variance parameters. Findings should be interpreted considering minimum effects in education that are relevant to education policy and practice.
Mathematical modeling has come into prominence during the last few decades in many countries' mathematics teaching curricula. It combines real life situations with mathematical context. Although evaluating students' mathematical modeling performances with a unique Likert type instrument is questionable, having an instrument about their self-efficacy beliefs in mathematical modeling may help to comment about their ideas related to their competencies in mathematical modeling. The purpose of this study is to develop a reliable and valid measurement scale to determine mathematical modeling self-efficacy of mathematics teacher candidates. For this purpose, the draft and final form of the scale were applied to a total of 562 pre-service elementary mathematics teachers from various public universities in Turkey. The findings of study revealed that the scale is unidimensional according to the results of exploratory factor analysis. The unidimensionality of the scale was validated by confirmatory factor analysis. The reliability of mathematical modeling self-efficacy scale was very high (.97). Finally, it was found that this scale is an appropriate measurement tool to evaluate students' selfefficacy beliefs on their mathematical modeling competencies. Some suggestions related to the scale and for further studies were given at the end.
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