C) From deciphering the writing they left behind
Their spirits where committed to what they believed in, and their attitude was positive and they didn't question there leaders.
Answer: unreliability
Explanation: Some of the problems that determine the quality of an experiment are reliability and validity.
Reliability considers the consistency of the experiment. In the example above, the result of the second sample is inconsistent with the result of the first sample, making Watt's research unreliable. That is, it does not reflect the ratings of a larger population. This problem can be solved by increasing the sample size, such that the average ratings are more reflective of a wider audience.
Validity considers the accuracy of the experiment. A lack of reliability of an experiment will likely make the result invalid as well, but this is not always the case.
