
Originally Posted by
Papewaio
Correlations.
False assumptions, based on bivariate correlations, based on anecdotal evidence. That is what the Fuchs/Woessmann paper is about.
We show that, first, bivariate evidence on the relationship between computers and students’ educational achievement is highly misleading. Because computer availability at home is strongly correlated with other family-background characteristics, bivariate results on computer availability at home are severely biased. Still, simple bivariate correlations are what many commentators base their assessments on. Even high-quality documents such as the initial release of the PISA results, albeit cautioning about possible limitations to the interpretation of bivariate findings, reports the simple bivariate finding that “[s]tudents with higher values on the index of interest in computers tend to perform better on the combined reading literacy scale” (OECD 2001, p. 118). We show that the statistically significant positive correlation between the availability of computers at home and student performance in math and reading reverses into a statistically significantly negative one as soon as other family-background influences are extensively controlled for in multivariate regressions.
Second, similar to the case of computer availability at home, bivariate results on computer availability at school are severely biased because the availability of school computers is strongly correlated with the availability of other school resources. While the bivariate correlation between the availability of computers at school and student performance is strongly and statistically significantly positive, the correlation becomes small and statistically indistinguishable from zero once other school characteristics are held constant. The multivariate results illustrate how careless bivariate interpretations can lead to patently false conclusions.
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Fourth, the relationship between student achievement and the use of computers and the internet at school shows an inverted U-shape. That is, students who never use computers or the internet at school show lower performance than students who sometimes use computers or the internet at school. But students who use them several times a week perform even lower.
We offer two possible explanations for this pattern. On the one hand, teachers might refrain from using computers with students of a low ability level. Then, the first part of the pattern may simply reflect an ability bias, and the second part of the pattern may reflect that computer use might actually have decreased student learning, as has also been found in a previous quasi-experimental study (Angrist and Lavy 2002). On the other hand, assuming that there is no ability bias left after the extensive controls that we include in the regressions, the pattern might suggest that there is an optimal level of computer and internet use at school, substantially below a use intensity of several times a week.
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