From the paper:<p><pre><code>    &gt; a widely used and validated mental-health screening tool (i.e.,
    &gt; the Strengths and Difficulties Questionnaire or SDQ). The SDQ was
    &gt; was explicitly designed for children and generates measures of
    &gt; several distinct psychopathological constructs,  some of which
    &gt; are clearly related to the theorized effects of delayed school
    &gt; starts.

    &gt; we find that these effects are largely driven by a large
    &gt; reduction (effect size = -0.70) in a single SDQ construct: the
    &gt; SDQ’s inattention &#x2F; hyperactivity score (i.e., a mea-sure of self
    &gt; regulation).</code></pre>