PrepTest 33, Section 2, Question 17
Expert witness: Ten times, and in controlled circumstances, a single drop of the defendant's blood was allowed to fall onto the fabric. And in all ten cases, the stained area was much less than the expected 9.5 cm2. In fact, the stained area was always between 4.5 and 4.8 cm2. I conclude that a single drop of the defendant's blood stains much less than 9.5 cm2 of the fabric.
Expert witness: Ten times, and in controlled circumstances, a single drop of the defendant's blood was allowed to fall onto the fabric. And in all ten cases, the stained area was much less than the expected 9.5 cm2. In fact, the stained area was always between 4.5 and 4.8 cm2. I conclude that a single drop of the defendant's blood stains much less than 9.5 cm2 of the fabric.
Expert witness: Ten times, and in controlled circumstances, a single drop of the defendant's blood was allowed to fall onto the fabric. And in all ten cases, the stained area was much less than the expected 9.5 cm2. In fact, the stained area was always between 4.5 and 4.8 cm2. I conclude that a single drop of the defendant's blood stains much less than 9.5 cm2 of the fabric.
Expert witness: Ten times, and in controlled circumstances, a single drop of the defendant's blood was allowed to fall onto the fabric. And in all ten cases, the stained area was much less than the expected 9.5 cm2. In fact, the stained area was always between 4.5 and 4.8 cm2. I conclude that a single drop of the defendant's blood stains much less than 9.5 cm2 of the fabric.
Which one of the following, if true, most undermines the value of the evidence for the expert witness's conclusion?
If similar results had been found after 100 test drops of the defendant's blood, the evidence would be even stronger.
Expert witnesses have sometimes been known to fudge their data to accord with the prosecution's case.
In an eleventh test drop of the defendant's blood, the area stained was also less than 9.5 cm2�this time staining 9.3 cm2.
Another person's blood was substituted, and in otherwise identical circumstances, stained between 9.8 and 10.6 cm2 of the fabric.
Not all expert witnesses are the authorities in their fields that they claim to be.
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