Imaging should not usually be sooner than 24 hours - high background at this time produces false negatives.

Skin prick tests are not always accurate and may produce false negatives.

It produced negatives so tiny that five could fit on a penny.

These tests should be done before the patient starts on a gluten-free diet, otherwise they might produce false negatives.

It was of the box form type, slipping easily into an ordinary coat pocket, and producing negatives 1 x 2 inches.

Mr. Nixon made these pictures with cameras that produce negatives up to 14 by 17 inches in size.

The classic test may have produced false negatives, because the child's recognition of the dot did not lead to them cleaning it.

This process had the advantage that it produced negatives unlike the daguerreotype process.

Moreover, we have seen that, at certain times, the tests involve risks because they produce false negatives.

He uses a specially designed and constructed camera weighing 300 pounds to produce 14-by-20-inch negatives.