What measure of spread is used when your data distribution is symmetrical?
Answer: When the data distribution is symmetrical, the appropriate measure of spread is standard deviation. The reason is both sides of symmetrical distribution will have same spread.
Symmetrical distribution: Symmetrical distribution is one when both sides of the distribution are identical. The symmetrical distribution is bell shaped and mean, median and mode are equal in symmetrical distribution.
Standard deviation: Standard deviation is the measure of dispersion. It measures the deviation of a set of numbers from its mean. It is defined as the square root of means of the squared deviations from the arithmetic mean