What statistical measure is used to represent the speeds of the observed data set?

• A. Mean speed
• B. Median speed
• C. Mode speed
• D. Variance speed

Answer: (B)

The median speed is an appropriate statistical measure to represent the speeds of an observed data set, particularly when dealing with skewed distributions. The median provides the middle value of a data set when it is ordered from lowest to highest. This means that half of the observed speeds are below the median and half are above it, making it a robust measure that is less influenced by extreme values or outliers.

In the context of transportation studies, where traffic speeds can vary significantly due to factors such as congestion, incidents, or road conditions, the median can give a clearer picture of typical speeds experienced by users, rather than being skewed by a few unusually high or low speeds. This characteristic makes the median a reliable indicator for summarizing transportation data, especially when decisions regarding improvements or assessments need to be made based on typical user experiences.

Other statistical measures, such as mean speed, can also signify average conditions but may be affected by outliers. The mode represents the most frequently occurring speed but may not accurately capture the central tendency in a data set with a varied range of speeds. Variance, while useful for understanding the variability of speeds, does not provide a direct measure of central tendency. Therefore, the median stands out as the most suitable choice for this question.