Answer :
Final answer:
The statement that a z-value of 3 is used to achieve a 99.7% confidence level is true, corresponding to the 3-sigma rule of a normal distribution that indicates approximately 99.7% of data within three standard deviations from the mean.
Explanation:
The statement 'To obtain a 99.7 percent confidence level in a p chart, we would use a value of 3 for z' is true. The 99.7% confidence level corresponds to three standard deviations from the mean in a normal distribution. This is often referred to as the empirical rule or 3-sigma rule, indicating that approximately 99.7% of the data falls within three standard deviations (z-scores of -3 and 3) from the mean.
The value chosen for z reflects our tolerance for error, usually a Type I error where we incorrectly report the presence of an analyte when it is absent. A z-score of 3 is typically used to correspond to a very low probability of such an error, specifically a probability of 0.135% for detecting an analyte in an analyte-free sample.
