What does a z-statistic of 1.96 in an RCV calculation indicate?

What does a z-statistic of 1.96 in an RCV calculation indicate?

• A. Indicates 95% probability that the change is true and not random
• B. Gives 99% probability
• C. Indicates 90% probability
• D. Indicates 50% probability

Answer: (A)

A z-statistic of 1.96 corresponds to the two-sided 95% confidence level in a normal distribution. In an RCV calculation, this means the observed change is unlikely due to random variation alone, with about a 5% chance that such a change could occur by chance. In other words, there is roughly 95% confidence that the change is real and not just random fluctuation. Higher or lower confidence levels would require larger or smaller z-values (e.g., 2.58 for ~99%, 1.64 for ~90%).

A z-statistic of 1.96 corresponds to the two-sided 95% confidence level in a normal distribution. In an RCV calculation, this means the observed change is unlikely due to random variation alone, with about a 5% chance that such a change could occur by chance. In other words, there is roughly 95% confidence that the change is real and not just random fluctuation. Higher or lower confidence levels would require larger or smaller z-values (e.g., 2.58 for ~99%, 1.64 for ~90%).