\BeginKnitrBlock{exercise}\iffalse{-91-84-104-101-32-115-105-122-101-32-111-102-32-99-111-110-102-105-100-101-110-99-101-32-105-110-116-101-114-118-97-108-115-93-}\fi{}<div class="exercise"><span class="exercise" id="exr:unnamed-chunk-60"><strong>(\#exr:unnamed-chunk-60)  \iffalse (The size of confidence intervals) \fi{} </strong></span>What can you do to decrease the width of your confidence interval? Hint: think about the $SEM$!</div>\EndKnitrBlock{exercise}