The trial court did not abuse its discretion in excluding plaintiff’s expert witness’ opinion regarding the accused diabetes drug’s causing an increased risk of heart failure in diabetics. The expert relied on only one test, the authors of which noted that its results as to heart failure were anomalous and required comparison with other tests. The expert also did not consistently or correctly apply the Bradford Hill analysis, a method of testing whether medical studies prove causation. Since there was no other expert evidence of causation and the drug’s causing heart failure was not a matter within the common knowledge of laymen, the trial court also correctly granted defendants summary judgment upon excluding the one expert’s opinion.