A large clinical trial was designed to determine whether a certain vitamin improves the general health of adults. The investigat
ors first identified 85 variables that measure various aspects of the general health of adults. Because each adult in the clinical trial was to serve as his or her own control, the 85 variables were measured for each adult, both before taking the vitamin and after taking the vitamin for three months. The investigators then performed 85 matched-pair t-tests, one for each variable. They found statistically significant results at the 0.05 level in 2 of the variables, both in the direction of improved general health. Which of the following should the investigators conclude? (A) There is evidence that the vitamin improves the health of adults because 2 of the 85 tests were statistically significant.(B) There is evidence that the vitamin improves the health of adults because in clinical trials investigators typically underestimate the proportion of the population that is helped by a vitamin.(C) There is insufficient evidence that the vitamin improves the health of adults because at the 0.05 significance level, one could easily get statistically significant results in 2 out of 85 tests just due to chance variability.(D) There is insufficient evidence that the vitamin improves the health of adults because the sample size of 85 is not large enough to draw a conclusion.(E) No conclusion can be drawn because an even number of variables is needed for a matched-pairs design.
(C) There is insufficient evidence that the vitamin improves the health of adults because at the 0.05 significance level, one could easily get statistically significant results in 2 out of 85 tests just due to chance variability.
Explanation:
T- tests is statistical tool that is used to determine if between the mean values of two groups there is a significant difference present.
It is used to test the hypothesis of an assumption that can be applied to a particular set or group of people.
In the question above, Option C is the valid conclusion because from the t-test carried out a significant level of 0.05 occured in two variables out of 85. Therefore there is insufficient evidence to prove that vitamin C improves the health of Adults.
It is possible and it is regularly done. The procedure is called magnetic resonance imaging, or MRI for short, and it allows us to quantify the volume of the brain. It is done in clinical tests to see if someone is sick or has an injury and it is also used in experiments when we are researching cognitive ability.
