Quality control investigator: Upon testing samples of products from our supplier that were sent by our field inspectors from various manufacturing locations, our laboratory discovered that over 20 percent of the samples were defective. Since our supplier is contractually required to limit the rate of defects among items it manufactures for us to below 5 percent, it has violated its contract with us. The reasoning in the quality control investigator's argument is flawed in that the argument ['presumes, without providing justification, that the field inspectors were just as likely to choose a defective item for testing as they were to choose a nondefective item', 'presumes, without providing justification, that the field inspectors made an equal number of visits to each of the various manufacturing sites of the supplier', 'overlooks the possibility that the field inspectors tend to choose items for testing that they suspect are defective', 'bases its conclusion on too small a sample of items tested by the laboratory']