A research team conducted a critical study and using data they gathered in their random experiment a 95% confidence interval for the population mean was constructed. The team was not happy with the result because they felt the margin of error was much too large. All other things being equal, if they were to repeat the study what could they do to reduce the margin of error?
A) They could construct the confidence interval with a lower confidence level than they previously used.
B) They could include a greater number of subjects in the experiment.
C) They could reduce the population standard deviation ?.
D) All of the above are possible things for them to try.
E) None of the above will work because of the randomness in the experiment.