A digital marketing manager wants to determine whether conversion rates from the company’s latest email...

To determine whether the campaign’s conversion rates are about the same as the industry average or significantly different, the manager must consider not only the average value but also how much variation exists in the data. Standard deviation is the measure that captures the spread or variability of the data around the mean. This makes it essential when evaluating whether an observed conversion rate is unusually high, unusually low, or within a normal expected range compared with the industry. The mean gives the central average, but by itself it does not show whether a result is significantly different. The median identifies the middle value, which is useful in skewed data but not sufficient for judging statistical difference in this context. A bell curve describes the shape of a normal distribution rather than serving as the core numerical measure needed here. Since the question is about determining whether results differ meaningfully from an average benchmark, standard deviation is the most appropriate concept among the options provided.