The full sentence that Google search threw up is this: Genetic influences among the writing measures were significantly correlated (highest between the speeded measures writing fluency and handwriting copy), but there were also significant independent genetic influences between copy and samples and between fluency and samples. As far as I understand it, "speeded measures writing fluency" is not a phrase. Rather, it is saying that writing fluency and handwriting copy are both "speeded measures", which I suppose means measurements of someone doing something quickly or under time constraints.
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