Which statement best distinguishes confidence interval from margin of error?

• A. They are unrelated.
• B. Margin of error is the central tendency.
• C. Both describe the same concept.
• D. Confidence interval expresses uncertainty around the estimate; margin of error is the range of true value.

Answer: (D)

The main idea is that a confidence interval and the margin of error describe sampling uncertainty in two related but distinct ways. A confidence interval is the actual range of plausible values for the population parameter, built around the point estimate to reflect what could be true in repeated samples. It communicates how uncertain we are about the estimate by showing a span where the true value is likely to lie.

The margin of error is the size of that span—how far the endpoints of the interval are from the estimate. In other words, the margin of error is the amount you add and subtract from the estimate to form the interval. The wider the margin, the more uncertainty we convey; the narrower, the more precision.

So, the statement that best distinguishes them is that the confidence interval expresses uncertainty around the estimate, while the margin of error determines the range (how wide that interval is) of the plausible true value.