Introduction to Descriptive Statistics: Using Mean, Median, and Standard Deviation

Which answer best describes standard deviation?

• a.Standard deviation is a measure of the spread of a dataset.
• b.Standard deviation indicates how much individual values vary from the mean.
• c.Standard deviation helps scientists summarize how much variation there is in a dataset or population.
• d.All of the answers are correct.

Mean is another word for

• a.average
• b.median
• c.standard deviation
• d.dataset

If the mean score for two different datasets is the same, the standard deviation will necessarily be the same.

• a.true
• b.false

If a dataset is evenly distributed around the mean, this is called a

• a.normal distribution
• b.Gaussian distribution
• c.bell curve
• d.All of the answers are correct.

The shape of a graph with a normal distribution (equation below) is defined by

• a.the mean and the median.
• b.the mean and the standard deviation.
• c.the median and the standard deviation.
• d.the standard deviation alone.

Look at the rainfall totals for the first five months of the year in Bisbee, AZ (table below). What is the mean rainfall in Bisbee for January through May?

• a.18.5 mm
• b.23 mm
• c.24 mm
• d.33 mm

Look at the rainfall totals for the first five months of the year in Bisbee, AZ (table below). What is the median value for rainfall in Bisbee for January through May?

• a.18.5 mm
• b.23 mm
• c.24 mm
• d.33 mm

When a dataset has an even number of values, the median is

• a.the same as the mean of the entire dataset.
• b.the mean of the highest and lowest values in the dataset.
• c.the mean of the two middlemost values in the dataset.
• d.none of the answers

If an experiment is repeated correctly several times, it should yield

• a.a distribution of measurements around some central value.
• b.a single value that is obtained each and every time.
• c.widely and randomly varying results.
• d.unpredictable results.

Students in two science classes took an exam. Both classes had the same mean score of 76. However Class #1 showed a standard deviation of 10, while Class #2 showed a standard deviation of 16. This means that

• a.Class #2 had better test scores overall than Class #1.
• b.there was a wider range of scores in Class #1 than in Class #2.
• c.there was a wider range of scores in Class #2 than in Class #1.
• d.the average score of Class #2 was 6 points higher than the average score in Class #1.

If a distribution is “non-normal,” it cannot be used to help scientists summarize datasets.

• a.true
• b.false

Descriptive statistics can be used to summarize

• a.the distribution of test scores in a class.
• b.how genetic traits evolve from one generation to the next.
• c.the relative velocities of gas molecules.
• d.All of the answers are correct.