EXAMPLE 3.33 The Product Doesn’t Work!

Two scientists published a paper claiming to have developed a very exciting new method to detect ovarian cancer using blood samples. The potential market for such a procedure is substantial, and there is no specific screening test currently available. When other scientists were unable to reproduce the results in different labs, the original work was examined more carefully. The original study used blood samples from women with ovarian cancer and from healthy controls. The blood samples were all analyzed using a mass spectrometer. The control samples were analyzed on one day and the cancer samples were analyzed on the next day. This design was flawed because it could not control for changes over time in the measuring instrument.³³